2022-10-05 22:15:10

by Jason A. Donenfeld

Subject: [PATCH v1 0/5] treewide cleanup of random integer usage

Hi folks,

This is a five part treewide cleanup of random integer handling. The
rules for random integers are:

- If you want a secure or an insecure random u64, use get_random_u64().
- If you want a secure or an insecure random u32, use get_random_u32().
* The old function prandom_u32() has been deprecated for a while now
and is just a wrapper around get_random_u32().
- If you want a secure or an insecure random u16, use get_random_u16().
- If you want a secure or an insecure random u8, use get_random_u8().
- If you want secure or insecure random bytes, use get_random_bytes().
* The old function prandom_bytes() has been deprecated for a while now
and has long been a wrapper around get_random_bytes().
- If you want a non-uniform random u32, u16, or u8 bounded by a certain
open interval maximum, use prandom_u32_max().
* I say "non-uniform", because it doesn't do any rejection sampling or
divisions. Hence, it stays within the prandom_* namespace.

These rules ought to be applied uniformly, so that we can clean up the
deprecated functions, and earn the benefits of using the modern
functions. In particular, in addition to the boring substitutions, this
patchset accomplishes a few nice effects:

- By using prandom_u32_max() with an upper-bound that the compiler can
prove at compile-time is ≤65536 or ≤256, internally get_random_u16()
or get_random_u8() is used, which wastes fewer batched random bytes,
and hence has higher throughput.

- By using prandom_u32_max() instead of %, when the upper-bound is not a
constant, division is still avoided, because prandom_u32_max() uses
a faster multiplication-based trick instead.

- By using get_random_u16() or get_random_u8() in cases where the return
value is intended to indeed be a u16 or a u8, we waste fewer batched
random bytes, and hence have higher throughput.

So, based on those rules and benefits from following them, this patchset
breaks down into the following five steps:

1) Replace `prandom_u32() % max` and variants thereof with
prandom_u32_max(max).

2) Replace `(type)get_random_u32()` and variants thereof with
get_random_u16() or get_random_u8(). I took the pains to actually
look and see what every lvalue type was across the entire tree.

3) Replace remaining deprecated uses of prandom_u32() with
get_random_u32().

4) Replace remaining deprecated uses of prandom_bytes() with
get_random_bytes().

5) Remove the deprecated and now-unused prandom_u32() and
prandom_bytes() inline wrapper functions.

I was thinking of taking this through my random.git tree (on which this
series is currently based) and submitting it near the end of the merge
window, or waiting for the very end of the 6.1 cycle when there will be
the fewest new patches brewing. If somebody with some treewide-cleanup
experience might share some wisdom about what the best timing usually
winds up being, I'm all ears.

I've CC'd get_maintainers.pl, which is a pretty big list. Probably some
portion of those are going to bounce, too, and everytime you reply to
this thread, you'll have to deal with a bunch of bounces coming
immediately after. And a recipient list this big will probably dock my
email domain's spam reputation, at least temporarily. Sigh. I think
that's just how it goes with treewide cleanups though. Again, let me
know if I'm doing it wrong.

Please take a look!

Thanks,
Jason

Cc: Ajay Singh <[email protected]>
Cc: Akinobu Mita <[email protected]>
Cc: Alexandre Torgue <[email protected]>
Cc: Amitkumar Karwar <[email protected]>
Cc: Andreas Dilger <[email protected]>
Cc: Andreas Färber <[email protected]>
Cc: Andreas Noever <[email protected]>
Cc: Andrew Lunn <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andrii Nakryiko <[email protected]>
Cc: Andy Gospodarek <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: Anil S Keshavamurthy <[email protected]>
Cc: Anna Schumaker <[email protected]>
Cc: Arend van Spriel <[email protected]>
Cc: Ayush Sawal <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Chao Yu <[email protected]>
Cc: Christoph Böhmwalder <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Chuck Lever <[email protected]>
Cc: Claudiu Beznea <[email protected]>
Cc: Cong Wang <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Cc: Darrick J. Wong <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Ahern <[email protected]>
Cc: David S. Miller <[email protected]>
Cc: Dennis Dalessandro <[email protected]>
Cc: Dick Kennedy <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Florian Westphal <[email protected]>
Cc: Franky Lin <[email protected]>
Cc: Ganapathi Bhat <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Gregory Greenman <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Hannes Reinecke <[email protected]>
Cc: Hans Verkuil <[email protected]>
Cc: Hante Meuleman <[email protected]>
Cc: Hao Luo <[email protected]>
Cc: Haoyue Xu <[email protected]>
Cc: Heiner Kallweit <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: Herbert Xu <[email protected]>
Cc: Hideaki YOSHIFUJI <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Igor Mitsyanko <[email protected]>
Cc: Ilya Dryomov <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jack Wang <[email protected]>
Cc: Jaegeuk Kim <[email protected]>
Cc: Jaehoon Chung <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Jamal Hadi Salim <[email protected]>
Cc: James E.J. Bottomley <[email protected]>
Cc: James Smart <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Jay Vosburgh <[email protected]>
Cc: Jean-Paul Roubelat <[email protected]>
Cc: Jeff Layton <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Jiri Pirko <[email protected]>
Cc: Johannes Berg <[email protected]>
Cc: John Fastabend <[email protected]>
Cc: John Stultz <[email protected]>
Cc: Jon Maloy <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Jozsef Kadlecsik <[email protected]>
Cc: Julian Anastasov <[email protected]>
Cc: KP Singh <[email protected]>
Cc: Kalle Valo <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Keith Busch <[email protected]>
Cc: Lars Ellenberg <[email protected]>
Cc: Leon Romanovsky <[email protected]>
Cc: Manish Rangankar <[email protected]>
Cc: Manivannan Sadhasivam <[email protected]>
Cc: Marcelo Ricardo Leitner <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Martin K. Petersen <[email protected]>
Cc: Martin KaFai Lau <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Mauro Carvalho Chehab <[email protected]>
Cc: Maxime Coquelin <[email protected]>
Cc: Md. Haris Iqbal <[email protected]>
Cc: Michael Chan <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Michael Jamet <[email protected]>
Cc: Michal Januszewski <[email protected]>
Cc: Mika Westerberg <[email protected]>
Cc: Miquel Raynal <[email protected]>
Cc: Namjae Jeon <[email protected]>
Cc: Naveen N. Rao <[email protected]>
Cc: Neil Horman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Nilesh Javali <[email protected]>
Cc: OGAWA Hirofumi <[email protected]>
Cc: Pablo Neira Ayuso <[email protected]>
Cc: Paolo Abeni <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Philipp Reisner <[email protected]>
Cc: Potnuri Bharat Teja <[email protected]>
Cc: Pravin B Shelar <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Rohit Maheshwari <[email protected]>
Cc: Russell King <[email protected]>
Cc: Sagi Grimberg <[email protected]>
Cc: Santosh Shilimkar <[email protected]>
Cc: Sergey Matyukevich <[email protected]>
Cc: Sharvari Harisangam <[email protected]>
Cc: Simon Horman <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Stanislav Fomichev <[email protected]>
Cc: Steffen Klassert <[email protected]>
Cc: Stephen Boyd <[email protected]>
Cc: Stephen Hemminger <[email protected]>
Cc: Sungjong Seo <[email protected]>
Cc: Theodore Ts'o <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Thomas Graf <[email protected]>
Cc: Thomas Sailer <[email protected]>
Cc: Toke Høiland-Jørgensen <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: Ulf Hansson <[email protected]>
Cc: Varun Prakash <[email protected]>
Cc: Veaceslav Falico <[email protected]>
Cc: Vignesh Raghavendra <[email protected]>
Cc: Vinay Kumar Yadav <[email protected]>
Cc: Vinod Koul <[email protected]>
Cc: Vlad Yasevich <[email protected]>
Cc: Wenpeng Liang <[email protected]>
Cc: Xinming Hu <[email protected]>
Cc: Xiubo Li <[email protected]>
Cc: Yehezkel Bernat <[email protected]>
Cc: Ying Xue <[email protected]>
Cc: Yishai Hadas <[email protected]>
Cc: Yonghong Song <[email protected]>
Cc: Yury Norov <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]

Jason A. Donenfeld (5):
treewide: use prandom_u32_max() when possible
treewide: use get_random_{u8,u16}() when possible
treewide: use get_random_u32() when possible
treewide: use get_random_bytes when possible
prandom: remove unused functions

Documentation/networking/filter.rst | 2 +-
arch/powerpc/crypto/crc-vpmsum_test.c | 2 +-
arch/x86/mm/pat/cpa-test.c | 4 +-
block/blk-crypto-fallback.c | 2 +-
crypto/async_tx/raid6test.c | 2 +-
crypto/testmgr.c | 94 +++++++++----------
drivers/block/drbd/drbd_receiver.c | 4 +-
drivers/dma/dmatest.c | 2 +-
drivers/infiniband/core/cma.c | 2 +-
drivers/infiniband/hw/cxgb4/cm.c | 4 +-
drivers/infiniband/hw/cxgb4/id_table.c | 4 +-
drivers/infiniband/hw/hfi1/tid_rdma.c | 2 +-
drivers/infiniband/hw/hns/hns_roce_ah.c | 5 +-
drivers/infiniband/hw/mlx4/mad.c | 2 +-
drivers/infiniband/ulp/ipoib/ipoib_cm.c | 2 +-
drivers/infiniband/ulp/rtrs/rtrs-clt.c | 3 +-
drivers/md/raid5-cache.c | 2 +-
drivers/media/common/v4l2-tpg/v4l2-tpg-core.c | 2 +-
.../media/test-drivers/vivid/vivid-radio-rx.c | 4 +-
drivers/mmc/core/core.c | 4 +-
drivers/mmc/host/dw_mmc.c | 2 +-
drivers/mtd/nand/raw/nandsim.c | 8 +-
drivers/mtd/tests/mtd_nandecctest.c | 12 +--
drivers/mtd/tests/speedtest.c | 2 +-
drivers/mtd/tests/stresstest.c | 19 +---
drivers/mtd/ubi/debug.c | 2 +-
drivers/mtd/ubi/debug.h | 6 +-
drivers/net/bonding/bond_main.c | 2 +-
drivers/net/ethernet/broadcom/bnxt/bnxt.c | 2 +-
drivers/net/ethernet/broadcom/cnic.c | 5 +-
.../chelsio/inline_crypto/chtls/chtls_cm.c | 4 +-
.../chelsio/inline_crypto/chtls/chtls_io.c | 4 +-
drivers/net/ethernet/rocker/rocker_main.c | 8 +-
drivers/net/hamradio/baycom_epp.c | 2 +-
drivers/net/hamradio/hdlcdrv.c | 2 +-
drivers/net/hamradio/yam.c | 2 +-
drivers/net/phy/at803x.c | 2 +-
drivers/net/wireguard/selftest/allowedips.c | 16 ++--
.../broadcom/brcm80211/brcmfmac/p2p.c | 2 +-
.../net/wireless/intel/iwlwifi/mvm/mac-ctxt.c | 2 +-
.../net/wireless/marvell/mwifiex/cfg80211.c | 4 +-
.../wireless/microchip/wilc1000/cfg80211.c | 2 +-
.../net/wireless/quantenna/qtnfmac/cfg80211.c | 2 +-
drivers/nvme/common/auth.c | 2 +-
drivers/scsi/cxgbi/cxgb4i/cxgb4i.c | 4 +-
drivers/scsi/fcoe/fcoe_ctlr.c | 4 +-
drivers/scsi/lpfc/lpfc_hbadisc.c | 6 +-
drivers/scsi/qedi/qedi_main.c | 2 +-
drivers/target/iscsi/cxgbit/cxgbit_cm.c | 2 +-
drivers/thunderbolt/xdomain.c | 2 +-
drivers/video/fbdev/uvesafb.c | 2 +-
fs/ceph/inode.c | 2 +-
fs/ceph/mdsmap.c | 2 +-
fs/exfat/inode.c | 2 +-
fs/ext2/ialloc.c | 2 +-
fs/ext4/ialloc.c | 4 +-
fs/ext4/ioctl.c | 4 +-
fs/ext4/mmp.c | 2 +-
fs/ext4/super.c | 7 +-
fs/f2fs/gc.c | 2 +-
fs/f2fs/namei.c | 2 +-
fs/f2fs/segment.c | 8 +-
fs/fat/inode.c | 2 +-
fs/nfsd/nfs4state.c | 4 +-
fs/ubifs/debug.c | 10 +-
fs/ubifs/journal.c | 2 +-
fs/ubifs/lpt_commit.c | 14 +--
fs/ubifs/tnc_commit.c | 2 +-
fs/xfs/libxfs/xfs_alloc.c | 2 +-
fs/xfs/libxfs/xfs_ialloc.c | 4 +-
fs/xfs/xfs_error.c | 2 +-
fs/xfs/xfs_icache.c | 2 +-
fs/xfs/xfs_log.c | 2 +-
include/linux/prandom.h | 12 ---
include/net/netfilter/nf_queue.h | 2 +-
include/net/red.h | 2 +-
include/net/sock.h | 2 +-
kernel/kcsan/selftest.c | 4 +-
kernel/time/clocksource.c | 2 +-
lib/fault-inject.c | 2 +-
lib/find_bit_benchmark.c | 4 +-
lib/random32.c | 4 +-
lib/reed_solomon/test_rslib.c | 12 +--
lib/sbitmap.c | 4 +-
lib/test_fprobe.c | 2 +-
lib/test_kprobes.c | 2 +-
lib/test_list_sort.c | 2 +-
lib/test_objagg.c | 2 +-
lib/test_rhashtable.c | 6 +-
lib/test_vmalloc.c | 19 +---
lib/uuid.c | 2 +-
mm/shmem.c | 2 +-
net/802/garp.c | 2 +-
net/802/mrp.c | 2 +-
net/ceph/mon_client.c | 2 +-
net/ceph/osd_client.c | 2 +-
net/core/neighbour.c | 2 +-
net/core/pktgen.c | 47 +++++-----
net/core/stream.c | 2 +-
net/dccp/ipv4.c | 4 +-
net/ipv4/datagram.c | 2 +-
net/ipv4/igmp.c | 6 +-
net/ipv4/inet_connection_sock.c | 2 +-
net/ipv4/inet_hashtables.c | 2 +-
net/ipv4/ip_output.c | 2 +-
net/ipv4/route.c | 2 +-
net/ipv4/tcp_cdg.c | 2 +-
net/ipv4/tcp_ipv4.c | 4 +-
net/ipv4/udp.c | 2 +-
net/ipv6/addrconf.c | 8 +-
net/ipv6/ip6_flowlabel.c | 2 +-
net/ipv6/mcast.c | 10 +-
net/ipv6/output_core.c | 2 +-
net/mac80211/rc80211_minstrel_ht.c | 2 +-
net/mac80211/scan.c | 2 +-
net/netfilter/ipvs/ip_vs_conn.c | 2 +-
net/netfilter/ipvs/ip_vs_twos.c | 4 +-
net/netfilter/nf_nat_core.c | 4 +-
net/netfilter/xt_statistic.c | 2 +-
net/openvswitch/actions.c | 2 +-
net/packet/af_packet.c | 2 +-
net/rds/bind.c | 2 +-
net/sched/act_gact.c | 2 +-
net/sched/act_sample.c | 2 +-
net/sched/sch_cake.c | 8 +-
net/sched/sch_netem.c | 22 ++---
net/sched/sch_pie.c | 2 +-
net/sched/sch_sfb.c | 2 +-
net/sctp/socket.c | 4 +-
net/sunrpc/auth_gss/gss_krb5_wrap.c | 4 +-
net/sunrpc/cache.c | 2 +-
net/sunrpc/xprt.c | 2 +-
net/sunrpc/xprtsock.c | 2 +-
net/tipc/socket.c | 2 +-
net/unix/af_unix.c | 2 +-
net/xfrm/xfrm_state.c | 2 +-
136 files changed, 304 insertions(+), 339 deletions(-)

--
2.37.3

2022-10-05 22:15:10

by Jason A. Donenfeld

Subject: [PATCH v1 2/5] treewide: use get_random_{u8,u16}() when possible

Rather than truncate a 32-bit value to a 16-bit value or an 8-bit value,
simply use the get_random_{u8,u16}() functions, which are faster than
wasting the additional bytes from a 32-bit value.

Signed-off-by: Jason A. Donenfeld <[email protected]>
---
crypto/testmgr.c | 8 ++++----
drivers/media/common/v4l2-tpg/v4l2-tpg-core.c | 2 +-
drivers/media/test-drivers/vivid/vivid-radio-rx.c | 4 ++--
.../net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c | 2 +-
drivers/net/hamradio/baycom_epp.c | 2 +-
drivers/net/hamradio/hdlcdrv.c | 2 +-
drivers/net/hamradio/yam.c | 2 +-
drivers/net/wireguard/selftest/allowedips.c | 4 ++--
drivers/scsi/lpfc/lpfc_hbadisc.c | 6 +++---
lib/test_vmalloc.c | 2 +-
net/dccp/ipv4.c | 4 ++--
net/ipv4/datagram.c | 2 +-
net/ipv4/ip_output.c | 2 +-
net/ipv4/tcp_ipv4.c | 4 ++--
net/mac80211/scan.c | 2 +-
net/netfilter/nf_nat_core.c | 4 ++--
net/sched/sch_cake.c | 6 +++---
net/sched/sch_sfb.c | 2 +-
net/sctp/socket.c | 2 +-
19 files changed, 31 insertions(+), 31 deletions(-)

diff --git a/crypto/testmgr.c b/crypto/testmgr.c
index be45217acde4..981c637fa2ed 100644
--- a/crypto/testmgr.c
+++ b/crypto/testmgr.c
@@ -927,7 +927,7 @@ static void generate_random_bytes(u8 *buf, size_t count)
b = 0xff;
break;
default:
- b = (u8)prandom_u32();
+ b = get_random_u8();
break;
}
memset(buf, b, count);
@@ -935,8 +935,8 @@ static void generate_random_bytes(u8 *buf, size_t count)
break;
case 2:
/* Ascending or descending bytes, plus optional mutations */
- increment = (u8)prandom_u32();
- b = (u8)prandom_u32();
+ increment = get_random_u8();
+ b = get_random_u8();
for (i = 0; i < count; i++, b += increment)
buf[i] = b;
mutate_buffer(buf, count);
@@ -944,7 +944,7 @@ static void generate_random_bytes(u8 *buf, size_t count)
default:
/* Fully random bytes */
for (i = 0; i < count; i++)
- buf[i] = (u8)prandom_u32();
+ buf[i] = get_random_u8();
}
}

diff --git a/drivers/media/common/v4l2-tpg/v4l2-tpg-core.c b/drivers/media/common/v4l2-tpg/v4l2-tpg-core.c
index 9b7bcdce6e44..303d02b1d71c 100644
--- a/drivers/media/common/v4l2-tpg/v4l2-tpg-core.c
+++ b/drivers/media/common/v4l2-tpg/v4l2-tpg-core.c
@@ -870,7 +870,7 @@ static void precalculate_color(struct tpg_data *tpg, int k)
g = tpg_colors[col].g;
b = tpg_colors[col].b;
} else if (tpg->pattern == TPG_PAT_NOISE) {
- r = g = b = prandom_u32_max(256);
+ r = g = b = get_random_u8();
} else if (k == TPG_COLOR_RANDOM) {
r = g = b = tpg->qual_offset + prandom_u32_max(196);
} else if (k >= TPG_COLOR_RAMP) {
diff --git a/drivers/media/test-drivers/vivid/vivid-radio-rx.c b/drivers/media/test-drivers/vivid/vivid-radio-rx.c
index 232cab508f48..8bd09589fb15 100644
--- a/drivers/media/test-drivers/vivid/vivid-radio-rx.c
+++ b/drivers/media/test-drivers/vivid/vivid-radio-rx.c
@@ -104,8 +104,8 @@ ssize_t vivid_radio_rx_read(struct file *file, char __user *buf,
break;
case 2:
rds.block |= V4L2_RDS_BLOCK_ERROR;
- rds.lsb = prandom_u32_max(256);
- rds.msb = prandom_u32_max(256);
+ rds.lsb = get_random_u8();
+ rds.msb = get_random_u8();
break;
case 3: /* Skip block altogether */
if (i)
diff --git a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c
index ddfe9208529a..ac452a0111a9 100644
--- a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c
+++ b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c
@@ -1467,7 +1467,7 @@ static void make_established(struct sock *sk, u32 snd_isn, unsigned int opt)
tp->write_seq = snd_isn;
tp->snd_nxt = snd_isn;
tp->snd_una = snd_isn;
- inet_sk(sk)->inet_id = prandom_u32();
+ inet_sk(sk)->inet_id = get_random_u16();
assign_rxopt(sk, opt);

if (tp->rcv_wnd > (RCV_BUFSIZ_M << 10))
diff --git a/drivers/net/hamradio/baycom_epp.c b/drivers/net/hamradio/baycom_epp.c
index 7df78a721b04..791b4a53d69f 100644
--- a/drivers/net/hamradio/baycom_epp.c
+++ b/drivers/net/hamradio/baycom_epp.c
@@ -438,7 +438,7 @@ static int transmit(struct baycom_state *bc, int cnt, unsigned char stat)
if ((--bc->hdlctx.slotcnt) > 0)
return 0;
bc->hdlctx.slotcnt = bc->ch_params.slottime;
- if (prandom_u32_max(256) > bc->ch_params.ppersist)
+ if (get_random_u8() > bc->ch_params.ppersist)
return 0;
}
}
diff --git a/drivers/net/hamradio/hdlcdrv.c b/drivers/net/hamradio/hdlcdrv.c
index 360d041a62c4..6c6f11d3d0aa 100644
--- a/drivers/net/hamradio/hdlcdrv.c
+++ b/drivers/net/hamradio/hdlcdrv.c
@@ -377,7 +377,7 @@ void hdlcdrv_arbitrate(struct net_device *dev, struct hdlcdrv_state *s)
if ((--s->hdlctx.slotcnt) > 0)
return;
s->hdlctx.slotcnt = s->ch_params.slottime;
- if (prandom_u32_max(256) > s->ch_params.ppersist)
+ if (get_random_u8() > s->ch_params.ppersist)
return;
start_tx(dev, s);
}
diff --git a/drivers/net/hamradio/yam.c b/drivers/net/hamradio/yam.c
index 97a6cc5c7ae8..2ed2f836f09a 100644
--- a/drivers/net/hamradio/yam.c
+++ b/drivers/net/hamradio/yam.c
@@ -626,7 +626,7 @@ static void yam_arbitrate(struct net_device *dev)
yp->slotcnt = yp->slot / 10;

/* is random > persist ? */
- if (prandom_u32_max(256) > yp->pers)
+ if (get_random_u8() > yp->pers)
return;

yam_start_tx(dev, yp);
diff --git a/drivers/net/wireguard/selftest/allowedips.c b/drivers/net/wireguard/selftest/allowedips.c
index 41db10f9be49..dd897c0740a2 100644
--- a/drivers/net/wireguard/selftest/allowedips.c
+++ b/drivers/net/wireguard/selftest/allowedips.c
@@ -310,7 +310,7 @@ static __init bool randomized_test(void)
for (k = 0; k < 4; ++k)
mutated[k] = (mutated[k] & mutate_mask[k]) |
(~mutate_mask[k] &
- prandom_u32_max(256));
+ get_random_u8());
cidr = prandom_u32_max(32) + 1;
peer = peers[prandom_u32_max(NUM_PEERS)];
if (wg_allowedips_insert_v4(&t,
@@ -354,7 +354,7 @@ static __init bool randomized_test(void)
for (k = 0; k < 4; ++k)
mutated[k] = (mutated[k] & mutate_mask[k]) |
(~mutate_mask[k] &
- prandom_u32_max(256));
+ get_random_u8());
cidr = prandom_u32_max(128) + 1;
peer = peers[prandom_u32_max(NUM_PEERS)];
if (wg_allowedips_insert_v6(&t,
diff --git a/drivers/scsi/lpfc/lpfc_hbadisc.c b/drivers/scsi/lpfc/lpfc_hbadisc.c
index 2645def612e6..26d1779cb570 100644
--- a/drivers/scsi/lpfc/lpfc_hbadisc.c
+++ b/drivers/scsi/lpfc/lpfc_hbadisc.c
@@ -2150,8 +2150,8 @@ lpfc_check_pending_fcoe_event(struct lpfc_hba *phba, uint8_t unreg_fcf)
* This function makes an running random selection decision on FCF record to
* use through a sequence of @fcf_cnt eligible FCF records with equal
* probability. To perform integer manunipulation of random numbers with
- * size unit32_t, the lower 16 bits of the 32-bit random number returned
- * from prandom_u32() are taken as the random random number generated.
+ * size unit32_t, a 16-bit random number returned from get_random_u16() is
+ * taken as the random random number generated.
*
* Returns true when outcome is for the newly read FCF record should be
* chosen; otherwise, return false when outcome is for keeping the previously
@@ -2163,7 +2163,7 @@ lpfc_sli4_new_fcf_random_select(struct lpfc_hba *phba, uint32_t fcf_cnt)
uint32_t rand_num;

/* Get 16-bit uniform random number */
- rand_num = 0xFFFF & prandom_u32();
+ rand_num = get_random_u16();

/* Decision with probability 1/fcf_cnt */
if ((fcf_cnt * rand_num) < 0xFFFF)
diff --git a/lib/test_vmalloc.c b/lib/test_vmalloc.c
index 56ffaa8dd3f6..0131ed2cd1bd 100644
--- a/lib/test_vmalloc.c
+++ b/lib/test_vmalloc.c
@@ -80,7 +80,7 @@ static int random_size_align_alloc_test(void)
int i;

for (i = 0; i < test_loop_count; i++) {
- rnd = prandom_u32();
+ rnd = get_random_u8();

/*
* Maximum 1024 pages, if PAGE_SIZE is 4096.
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index da6e3b20cd75..301799e7fa56 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -123,7 +123,7 @@ int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
inet->inet_daddr,
inet->inet_sport,
inet->inet_dport);
- inet->inet_id = prandom_u32();
+ inet->inet_id = get_random_u16();

err = dccp_connect(sk);
rt = NULL;
@@ -422,7 +422,7 @@ struct sock *dccp_v4_request_recv_sock(const struct sock *sk,
RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt));
newinet->mc_index = inet_iif(skb);
newinet->mc_ttl = ip_hdr(skb)->ttl;
- newinet->inet_id = prandom_u32();
+ newinet->inet_id = get_random_u16();

if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL)
goto put_and_exit;
diff --git a/net/ipv4/datagram.c b/net/ipv4/datagram.c
index ffd57523331f..fefc5d855a66 100644
--- a/net/ipv4/datagram.c
+++ b/net/ipv4/datagram.c
@@ -71,7 +71,7 @@ int __ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len
reuseport_has_conns(sk, true);
sk->sk_state = TCP_ESTABLISHED;
sk_set_txhash(sk);
- inet->inet_id = prandom_u32();
+ inet->inet_id = get_random_u16();

sk_dst_set(sk, &rt->dst);
err = 0;
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 04e2034f2f8e..a4fbdbff14b3 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -172,7 +172,7 @@ int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk,
* Avoid using the hashed IP ident generator.
*/
if (sk->sk_protocol == IPPROTO_TCP)
- iph->id = (__force __be16)prandom_u32();
+ iph->id = (__force __be16)get_random_u16();
else
__ip_select_ident(net, iph, 1);
}
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 5b019ba2b9d2..747752980983 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -303,7 +303,7 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
inet->inet_daddr);
}

- inet->inet_id = prandom_u32();
+ inet->inet_id = get_random_u16();

if (tcp_fastopen_defer_connect(sk, &err))
return err;
@@ -1523,7 +1523,7 @@ struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
inet_csk(newsk)->icsk_ext_hdr_len = 0;
if (inet_opt)
inet_csk(newsk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
- newinet->inet_id = prandom_u32();
+ newinet->inet_id = get_random_u16();

/* Set ToS of the new socket based upon the value of incoming SYN.
* ECT bits are set later in tcp_init_transfer().
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index c4f2aeb31da3..6cab549cc421 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -641,7 +641,7 @@ static void ieee80211_send_scan_probe_req(struct ieee80211_sub_if_data *sdata,
if (flags & IEEE80211_PROBE_FLAG_RANDOM_SN) {
struct ieee80211_hdr *hdr = (void *)skb->data;
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
- u16 sn = get_random_u32();
+ u16 sn = get_random_u16();

info->control.flags |= IEEE80211_TX_CTRL_NO_SEQNO;
hdr->seq_ctrl =
diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c
index 7981be526f26..57c7686ac485 100644
--- a/net/netfilter/nf_nat_core.c
+++ b/net/netfilter/nf_nat_core.c
@@ -468,7 +468,7 @@ static void nf_nat_l4proto_unique_tuple(struct nf_conntrack_tuple *tuple,
if (range->flags & NF_NAT_RANGE_PROTO_OFFSET)
off = (ntohs(*keyptr) - ntohs(range->base_proto.all));
else
- off = prandom_u32();
+ off = get_random_u16();

attempts = range_size;
if (attempts > max_attempts)
@@ -490,7 +490,7 @@ static void nf_nat_l4proto_unique_tuple(struct nf_conntrack_tuple *tuple,
if (attempts >= range_size || attempts < 16)
return;
attempts /= 2;
- off = prandom_u32();
+ off = get_random_u16();
goto another_round;
}

diff --git a/net/sched/sch_cake.c b/net/sched/sch_cake.c
index a43a58a73d09..637ef1757931 100644
--- a/net/sched/sch_cake.c
+++ b/net/sched/sch_cake.c
@@ -2092,11 +2092,11 @@ static struct sk_buff *cake_dequeue(struct Qdisc *sch)

WARN_ON(host_load > CAKE_QUEUES);

- /* The shifted prandom_u32() is a way to apply dithering to
- * avoid accumulating roundoff errors
+ /* The get_random_u16() is a way to apply dithering to avoid
+ * accumulating roundoff errors
*/
flow->deficit += (b->flow_quantum * quantum_div[host_load] +
- (prandom_u32() >> 16)) >> 16;
+ get_random_u16()) >> 16;
list_move_tail(&flow->flowchain, &b->old_flows);

goto retry;
diff --git a/net/sched/sch_sfb.c b/net/sched/sch_sfb.c
index 2829455211f8..7eb70acb4d58 100644
--- a/net/sched/sch_sfb.c
+++ b/net/sched/sch_sfb.c
@@ -379,7 +379,7 @@ static int sfb_enqueue(struct sk_buff *skb, struct Qdisc *sch,
goto enqueue;
}

- r = prandom_u32() & SFB_MAX_PROB;
+ r = get_random_u16() & SFB_MAX_PROB;

if (unlikely(r < p_min)) {
if (unlikely(p_min > SFB_MAX_PROB / 2)) {
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 1e354ba44960..83628c347744 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -9448,7 +9448,7 @@ void sctp_copy_sock(struct sock *newsk, struct sock *sk,
newinet->inet_rcv_saddr = inet->inet_rcv_saddr;
newinet->inet_dport = htons(asoc->peer.port);
newinet->pmtudisc = inet->pmtudisc;
- newinet->inet_id = prandom_u32();
+ newinet->inet_id = get_random_u16();

newinet->uc_ttl = inet->uc_ttl;
newinet->mc_loop = 1;
--
2.37.3

2022-10-05 22:31:08

by Jason A. Donenfeld

Subject: [PATCH v1 1/5] treewide: use prandom_u32_max() when possible

Rather than incurring a division or requesting too many random bytes for
the given range, use the prandom_u32_max() function, which only takes
the minimum required bytes from the RNG and avoids divisions.

Signed-off-by: Jason A. Donenfeld <[email protected]>
---
arch/x86/mm/pat/cpa-test.c | 4 +-
crypto/testmgr.c | 86 +++++++++----------
drivers/block/drbd/drbd_receiver.c | 4 +-
drivers/infiniband/core/cma.c | 2 +-
drivers/infiniband/hw/cxgb4/id_table.c | 4 +-
drivers/infiniband/hw/hns/hns_roce_ah.c | 5 +-
drivers/infiniband/ulp/rtrs/rtrs-clt.c | 3 +-
drivers/mmc/core/core.c | 4 +-
drivers/mmc/host/dw_mmc.c | 2 +-
drivers/mtd/nand/raw/nandsim.c | 4 +-
drivers/mtd/tests/mtd_nandecctest.c | 10 +--
drivers/mtd/tests/stresstest.c | 17 +---
drivers/mtd/ubi/debug.c | 2 +-
drivers/mtd/ubi/debug.h | 6 +-
drivers/net/ethernet/broadcom/cnic.c | 3 +-
.../chelsio/inline_crypto/chtls/chtls_io.c | 4 +-
drivers/net/hamradio/baycom_epp.c | 2 +-
drivers/net/hamradio/hdlcdrv.c | 2 +-
drivers/net/hamradio/yam.c | 2 +-
drivers/net/phy/at803x.c | 2 +-
.../broadcom/brcm80211/brcmfmac/p2p.c | 2 +-
.../net/wireless/intel/iwlwifi/mvm/mac-ctxt.c | 2 +-
drivers/scsi/fcoe/fcoe_ctlr.c | 4 +-
drivers/scsi/qedi/qedi_main.c | 2 +-
fs/ceph/inode.c | 2 +-
fs/ceph/mdsmap.c | 2 +-
fs/ext4/super.c | 7 +-
fs/f2fs/gc.c | 2 +-
fs/f2fs/segment.c | 8 +-
fs/ubifs/debug.c | 8 +-
fs/ubifs/lpt_commit.c | 14 +--
fs/ubifs/tnc_commit.c | 2 +-
fs/xfs/libxfs/xfs_alloc.c | 2 +-
fs/xfs/libxfs/xfs_ialloc.c | 2 +-
fs/xfs/xfs_error.c | 2 +-
kernel/time/clocksource.c | 2 +-
lib/fault-inject.c | 2 +-
lib/find_bit_benchmark.c | 4 +-
lib/reed_solomon/test_rslib.c | 6 +-
lib/sbitmap.c | 4 +-
lib/test_list_sort.c | 2 +-
lib/test_vmalloc.c | 17 +---
net/ceph/mon_client.c | 2 +-
net/ceph/osd_client.c | 2 +-
net/core/neighbour.c | 2 +-
net/core/pktgen.c | 43 +++++-----
net/core/stream.c | 2 +-
net/ipv4/igmp.c | 6 +-
net/ipv4/inet_connection_sock.c | 2 +-
net/ipv4/inet_hashtables.c | 2 +-
net/ipv6/addrconf.c | 8 +-
net/ipv6/mcast.c | 10 +--
net/netfilter/ipvs/ip_vs_twos.c | 4 +-
net/packet/af_packet.c | 2 +-
net/sched/act_gact.c | 2 +-
net/sched/act_sample.c | 2 +-
net/sched/sch_netem.c | 4 +-
net/sctp/socket.c | 2 +-
net/sunrpc/cache.c | 2 +-
net/sunrpc/xprtsock.c | 2 +-
net/tipc/socket.c | 2 +-
net/xfrm/xfrm_state.c | 2 +-
62 files changed, 173 insertions(+), 196 deletions(-)

diff --git a/arch/x86/mm/pat/cpa-test.c b/arch/x86/mm/pat/cpa-test.c
index 0612a73638a8..423b21e80929 100644
--- a/arch/x86/mm/pat/cpa-test.c
+++ b/arch/x86/mm/pat/cpa-test.c
@@ -136,10 +136,10 @@ static int pageattr_test(void)
failed += print_split(&sa);

for (i = 0; i < NTEST; i++) {
- unsigned long pfn = prandom_u32() % max_pfn_mapped;
+ unsigned long pfn = prandom_u32_max(max_pfn_mapped);

addr[i] = (unsigned long)__va(pfn << PAGE_SHIFT);
- len[i] = prandom_u32() % NPAGES;
+ len[i] = prandom_u32_max(NPAGES);
len[i] = min_t(unsigned long, len[i], max_pfn_mapped - pfn - 1);

if (len[i] == 0)
diff --git a/crypto/testmgr.c b/crypto/testmgr.c
index 5349ffee6bbd..be45217acde4 100644
--- a/crypto/testmgr.c
+++ b/crypto/testmgr.c
@@ -855,9 +855,9 @@ static int prepare_keybuf(const u8 *key, unsigned int ksize,
/* Generate a random length in range [0, max_len], but prefer smaller values */
static unsigned int generate_random_length(unsigned int max_len)
{
- unsigned int len = prandom_u32() % (max_len + 1);
+ unsigned int len = prandom_u32_max(max_len + 1);

- switch (prandom_u32() % 4) {
+ switch (prandom_u32_max(4)) {
case 0:
return len % 64;
case 1:
@@ -874,14 +874,14 @@ static void flip_random_bit(u8 *buf, size_t size)
{
size_t bitpos;

- bitpos = prandom_u32() % (size * 8);
+ bitpos = prandom_u32_max(size * 8);
buf[bitpos / 8] ^= 1 << (bitpos % 8);
}

/* Flip a random byte in the given nonempty data buffer */
static void flip_random_byte(u8 *buf, size_t size)
{
- buf[prandom_u32() % size] ^= 0xff;
+ buf[prandom_u32_max(size)] ^= 0xff;
}

/* Sometimes make some random changes to the given nonempty data buffer */
@@ -891,15 +891,15 @@ static void mutate_buffer(u8 *buf, size_t size)
size_t i;

/* Sometimes flip some bits */
- if (prandom_u32() % 4 == 0) {
- num_flips = min_t(size_t, 1 << (prandom_u32() % 8), size * 8);
+ if (prandom_u32_max(4) == 0) {
+ num_flips = min_t(size_t, 1 << prandom_u32_max(8), size * 8);
for (i = 0; i < num_flips; i++)
flip_random_bit(buf, size);
}

/* Sometimes flip some bytes */
- if (prandom_u32() % 4 == 0) {
- num_flips = min_t(size_t, 1 << (prandom_u32() % 8), size);
+ if (prandom_u32_max(4) == 0) {
+ num_flips = min_t(size_t, 1 << prandom_u32_max(8), size);
for (i = 0; i < num_flips; i++)
flip_random_byte(buf, size);
}
@@ -915,11 +915,11 @@ static void generate_random_bytes(u8 *buf, size_t count)
if (count == 0)
return;

- switch (prandom_u32() % 8) { /* Choose a generation strategy */
+ switch (prandom_u32_max(8)) { /* Choose a generation strategy */
case 0:
case 1:
/* All the same byte, plus optional mutations */
- switch (prandom_u32() % 4) {
+ switch (prandom_u32_max(4)) {
case 0:
b = 0x00;
break;
@@ -959,24 +959,24 @@ static char *generate_random_sgl_divisions(struct test_sg_division *divs,
unsigned int this_len;
const char *flushtype_str;

- if (div == &divs[max_divs - 1] || prandom_u32() % 2 == 0)
+ if (div == &divs[max_divs - 1] || prandom_u32_max(2) == 0)
this_len = remaining;
else
- this_len = 1 + (prandom_u32() % remaining);
+ this_len = 1 + prandom_u32_max(remaining);
div->proportion_of_total = this_len;

- if (prandom_u32() % 4 == 0)
- div->offset = (PAGE_SIZE - 128) + (prandom_u32() % 128);
- else if (prandom_u32() % 2 == 0)
- div->offset = prandom_u32() % 32;
+ if (prandom_u32_max(4) == 0)
+ div->offset = (PAGE_SIZE - 128) + prandom_u32_max(128);
+ else if (prandom_u32_max(2) == 0)
+ div->offset = prandom_u32_max(32);
else
- div->offset = prandom_u32() % PAGE_SIZE;
- if (prandom_u32() % 8 == 0)
+ div->offset = prandom_u32_max(PAGE_SIZE);
+ if (prandom_u32_max(8) == 0)
div->offset_relative_to_alignmask = true;

div->flush_type = FLUSH_TYPE_NONE;
if (gen_flushes) {
- switch (prandom_u32() % 4) {
+ switch (prandom_u32_max(4)) {
case 0:
div->flush_type = FLUSH_TYPE_REIMPORT;
break;
@@ -988,7 +988,7 @@ static char *generate_random_sgl_divisions(struct test_sg_division *divs,

if (div->flush_type != FLUSH_TYPE_NONE &&
!(req_flags & CRYPTO_TFM_REQ_MAY_SLEEP) &&
- prandom_u32() % 2 == 0)
+ prandom_u32_max(2) == 0)
div->nosimd = true;

switch (div->flush_type) {
@@ -1035,7 +1035,7 @@ static void generate_random_testvec_config(struct testvec_config *cfg,

p += scnprintf(p, end - p, "random:");

- switch (prandom_u32() % 4) {
+ switch (prandom_u32_max(4)) {
case 0:
case 1:
cfg->inplace_mode = OUT_OF_PLACE;
@@ -1050,12 +1050,12 @@ static void generate_random_testvec_config(struct testvec_config *cfg,
break;
}

- if (prandom_u32() % 2 == 0) {
+ if (prandom_u32_max(2) == 0) {
cfg->req_flags |= CRYPTO_TFM_REQ_MAY_SLEEP;
p += scnprintf(p, end - p, " may_sleep");
}

- switch (prandom_u32() % 4) {
+ switch (prandom_u32_max(4)) {
case 0:
cfg->finalization_type = FINALIZATION_TYPE_FINAL;
p += scnprintf(p, end - p, " use_final");
@@ -1071,7 +1071,7 @@ static void generate_random_testvec_config(struct testvec_config *cfg,
}

if (!(cfg->req_flags & CRYPTO_TFM_REQ_MAY_SLEEP) &&
- prandom_u32() % 2 == 0) {
+ prandom_u32_max(2) == 0) {
cfg->nosimd = true;
p += scnprintf(p, end - p, " nosimd");
}
@@ -1084,7 +1084,7 @@ static void generate_random_testvec_config(struct testvec_config *cfg,
cfg->req_flags);
p += scnprintf(p, end - p, "]");

- if (cfg->inplace_mode == OUT_OF_PLACE && prandom_u32() % 2 == 0) {
+ if (cfg->inplace_mode == OUT_OF_PLACE && prandom_u32_max(2) == 0) {
p += scnprintf(p, end - p, " dst_divs=[");
p = generate_random_sgl_divisions(cfg->dst_divs,
ARRAY_SIZE(cfg->dst_divs),
@@ -1093,13 +1093,13 @@ static void generate_random_testvec_config(struct testvec_config *cfg,
p += scnprintf(p, end - p, "]");
}

- if (prandom_u32() % 2 == 0) {
- cfg->iv_offset = 1 + (prandom_u32() % MAX_ALGAPI_ALIGNMASK);
+ if (prandom_u32_max(2) == 0) {
+ cfg->iv_offset = 1 + prandom_u32_max(MAX_ALGAPI_ALIGNMASK);
p += scnprintf(p, end - p, " iv_offset=%u", cfg->iv_offset);
}

- if (prandom_u32() % 2 == 0) {
- cfg->key_offset = 1 + (prandom_u32() % MAX_ALGAPI_ALIGNMASK);
+ if (prandom_u32_max(2) == 0) {
+ cfg->key_offset = 1 + prandom_u32_max(MAX_ALGAPI_ALIGNMASK);
p += scnprintf(p, end - p, " key_offset=%u", cfg->key_offset);
}

@@ -1652,8 +1652,8 @@ static void generate_random_hash_testvec(struct shash_desc *desc,
vec->ksize = 0;
if (maxkeysize) {
vec->ksize = maxkeysize;
- if (prandom_u32() % 4 == 0)
- vec->ksize = 1 + (prandom_u32() % maxkeysize);
+ if (prandom_u32_max(4) == 0)
+ vec->ksize = 1 + prandom_u32_max(maxkeysize);
generate_random_bytes((u8 *)vec->key, vec->ksize);

vec->setkey_error = crypto_shash_setkey(desc->tfm, vec->key,
@@ -2218,13 +2218,13 @@ static void mutate_aead_message(struct aead_testvec *vec, bool aad_iv,
const unsigned int aad_tail_size = aad_iv ? ivsize : 0;
const unsigned int authsize = vec->clen - vec->plen;

- if (prandom_u32() % 2 == 0 && vec->alen > aad_tail_size) {
+ if (prandom_u32_max(2) == 0 && vec->alen > aad_tail_size) {
/* Mutate the AAD */
flip_random_bit((u8 *)vec->assoc, vec->alen - aad_tail_size);
- if (prandom_u32() % 2 == 0)
+ if (prandom_u32_max(2) == 0)
return;
}
- if (prandom_u32() % 2 == 0) {
+ if (prandom_u32_max(2) == 0) {
/* Mutate auth tag (assuming it's at the end of ciphertext) */
flip_random_bit((u8 *)vec->ctext + vec->plen, authsize);
} else {
@@ -2249,7 +2249,7 @@ static void generate_aead_message(struct aead_request *req,
const unsigned int ivsize = crypto_aead_ivsize(tfm);
const unsigned int authsize = vec->clen - vec->plen;
const bool inauthentic = (authsize >= MIN_COLLISION_FREE_AUTHSIZE) &&
- (prefer_inauthentic || prandom_u32() % 4 == 0);
+ (prefer_inauthentic || prandom_u32_max(4) == 0);

/* Generate the AAD. */
generate_random_bytes((u8 *)vec->assoc, vec->alen);
@@ -2257,7 +2257,7 @@ static void generate_aead_message(struct aead_request *req,
/* Avoid implementation-defined behavior. */
memcpy((u8 *)vec->assoc + vec->alen - ivsize, vec->iv, ivsize);

- if (inauthentic && prandom_u32() % 2 == 0) {
+ if (inauthentic && prandom_u32_max(2) == 0) {
/* Generate a random ciphertext. */
generate_random_bytes((u8 *)vec->ctext, vec->clen);
} else {
@@ -2321,8 +2321,8 @@ static void generate_random_aead_testvec(struct aead_request *req,

/* Key: length in [0, maxkeysize], but usually choose maxkeysize */
vec->klen = maxkeysize;
- if (prandom_u32() % 4 == 0)
- vec->klen = prandom_u32() % (maxkeysize + 1);
+ if (prandom_u32_max(4) == 0)
+ vec->klen = prandom_u32_max(maxkeysize + 1);
generate_random_bytes((u8 *)vec->key, vec->klen);
vec->setkey_error = crypto_aead_setkey(tfm, vec->key, vec->klen);

@@ -2331,8 +2331,8 @@ static void generate_random_aead_testvec(struct aead_request *req,

/* Tag length: in [0, maxauthsize], but usually choose maxauthsize */
authsize = maxauthsize;
- if (prandom_u32() % 4 == 0)
- authsize = prandom_u32() % (maxauthsize + 1);
+ if (prandom_u32_max(4) == 0)
+ authsize = prandom_u32_max(maxauthsize + 1);
if (prefer_inauthentic && authsize < MIN_COLLISION_FREE_AUTHSIZE)
authsize = MIN_COLLISION_FREE_AUTHSIZE;
if (WARN_ON(authsize > maxdatasize))
@@ -2342,7 +2342,7 @@ static void generate_random_aead_testvec(struct aead_request *req,

/* AAD, plaintext, and ciphertext lengths */
total_len = generate_random_length(maxdatasize);
- if (prandom_u32() % 4 == 0)
+ if (prandom_u32_max(4) == 0)
vec->alen = 0;
else
vec->alen = generate_random_length(total_len);
@@ -2958,8 +2958,8 @@ static void generate_random_cipher_testvec(struct skcipher_request *req,

/* Key: length in [0, maxkeysize], but usually choose maxkeysize */
vec->klen = maxkeysize;
- if (prandom_u32() % 4 == 0)
- vec->klen = prandom_u32() % (maxkeysize + 1);
+ if (prandom_u32_max(4) == 0)
+ vec->klen = prandom_u32_max(maxkeysize + 1);
generate_random_bytes((u8 *)vec->key, vec->klen);
vec->setkey_error = crypto_skcipher_setkey(tfm, vec->key, vec->klen);

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index af4c7d65490b..d8b1417dc503 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -781,7 +781,7 @@ static struct socket *drbd_wait_for_connect(struct drbd_connection *connection,

timeo = connect_int * HZ;
/* 28.5% random jitter */
- timeo += (prandom_u32() & 1) ? timeo / 7 : -timeo / 7;
+ timeo += prandom_u32_max(2) ? timeo / 7 : -timeo / 7;

err = wait_for_completion_interruptible_timeout(&ad->door_bell, timeo);
if (err <= 0)
@@ -1004,7 +1004,7 @@ static int conn_connect(struct drbd_connection *connection)
drbd_warn(connection, "Error receiving initial packet\n");
sock_release(s);
randomize:
- if (prandom_u32() & 1)
+ if (prandom_u32_max(2))
goto retry;
}
}
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index be317f2665a9..d460935e89eb 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -3759,7 +3759,7 @@ static int cma_alloc_any_port(enum rdma_ucm_port_space ps,

inet_get_local_port_range(net, &low, &high);
remaining = (high - low) + 1;
- rover = prandom_u32() % remaining + low;
+ rover = prandom_u32_max(remaining) + low;
retry:
if (last_used_port != rover) {
struct rdma_bind_list *bind_list;
diff --git a/drivers/infiniband/hw/cxgb4/id_table.c b/drivers/infiniband/hw/cxgb4/id_table.c
index f64e7e02b129..280d61466855 100644
--- a/drivers/infiniband/hw/cxgb4/id_table.c
+++ b/drivers/infiniband/hw/cxgb4/id_table.c
@@ -54,7 +54,7 @@ u32 c4iw_id_alloc(struct c4iw_id_table *alloc)

if (obj < alloc->max) {
if (alloc->flags & C4IW_ID_TABLE_F_RANDOM)
- alloc->last += prandom_u32() % RANDOM_SKIP;
+ alloc->last += prandom_u32_max(RANDOM_SKIP);
else
alloc->last = obj + 1;
if (alloc->last >= alloc->max)
@@ -85,7 +85,7 @@ int c4iw_id_table_alloc(struct c4iw_id_table *alloc, u32 start, u32 num,
alloc->start = start;
alloc->flags = flags;
if (flags & C4IW_ID_TABLE_F_RANDOM)
- alloc->last = prandom_u32() % RANDOM_SKIP;
+ alloc->last = prandom_u32_max(RANDOM_SKIP);
else
alloc->last = 0;
alloc->max = num;
diff --git a/drivers/infiniband/hw/hns/hns_roce_ah.c b/drivers/infiniband/hw/hns/hns_roce_ah.c
index 492b122d0521..480c062dd04f 100644
--- a/drivers/infiniband/hw/hns/hns_roce_ah.c
+++ b/drivers/infiniband/hw/hns/hns_roce_ah.c
@@ -41,9 +41,8 @@ static inline u16 get_ah_udp_sport(const struct rdma_ah_attr *ah_attr)
u16 sport;

if (!fl)
- sport = get_random_u32() %
- (IB_ROCE_UDP_ENCAP_VALID_PORT_MAX + 1 -
- IB_ROCE_UDP_ENCAP_VALID_PORT_MIN) +
+ sport = prandom_u32_max(IB_ROCE_UDP_ENCAP_VALID_PORT_MAX + 1 -
+ IB_ROCE_UDP_ENCAP_VALID_PORT_MIN) +
IB_ROCE_UDP_ENCAP_VALID_PORT_MIN;
else
sport = rdma_flow_label_to_udp_sport(fl);
diff --git a/drivers/infiniband/ulp/rtrs/rtrs-clt.c b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
index 449904dac0a9..e2a89d7f52df 100644
--- a/drivers/infiniband/ulp/rtrs/rtrs-clt.c
+++ b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
@@ -1511,8 +1511,7 @@ static void rtrs_clt_err_recovery_work(struct work_struct *work)
rtrs_clt_stop_and_destroy_conns(clt_path);
queue_delayed_work(rtrs_wq, &clt_path->reconnect_dwork,
msecs_to_jiffies(delay_ms +
- prandom_u32() %
- RTRS_RECONNECT_SEED));
+ prandom_u32_max(RTRS_RECONNECT_SEED)));
}

static struct rtrs_clt_path *alloc_path(struct rtrs_clt_sess *clt,
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index ef53a2578824..95fa8fb1d45f 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -97,8 +97,8 @@ static void mmc_should_fail_request(struct mmc_host *host,
!should_fail(&host->fail_mmc_request, data->blksz * data->blocks))
return;

- data->error = data_errors[prandom_u32() % ARRAY_SIZE(data_errors)];
- data->bytes_xfered = (prandom_u32() % (data->bytes_xfered >> 9)) << 9;
+ data->error = data_errors[prandom_u32_max(ARRAY_SIZE(data_errors))];
+ data->bytes_xfered = prandom_u32_max(data->bytes_xfered >> 9) << 9;
}

#else /* CONFIG_FAIL_MMC_REQUEST */
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 581614196a84..c78bbc22e0d1 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -1858,7 +1858,7 @@ static void dw_mci_start_fault_timer(struct dw_mci *host)
* Try to inject the error at random points during the data transfer.
*/
hrtimer_start(&host->fault_timer,
- ms_to_ktime(prandom_u32() % 25),
+ ms_to_ktime(prandom_u32_max(25)),
HRTIMER_MODE_REL);
}

diff --git a/drivers/mtd/nand/raw/nandsim.c b/drivers/mtd/nand/raw/nandsim.c
index 24beade95c7f..50bcf745e816 100644
--- a/drivers/mtd/nand/raw/nandsim.c
+++ b/drivers/mtd/nand/raw/nandsim.c
@@ -1405,9 +1405,9 @@ static void ns_do_bit_flips(struct nandsim *ns, int num)
if (bitflips && prandom_u32() < (1 << 22)) {
int flips = 1;
if (bitflips > 1)
- flips = (prandom_u32() % (int) bitflips) + 1;
+ flips = prandom_u32_max(bitflips) + 1;
while (flips--) {
- int pos = prandom_u32() % (num * 8);
+ int pos = prandom_u32_max(num * 8);
ns->buf.byte[pos / 8] ^= (1 << (pos % 8));
NS_WARN("read_page: flipping bit %d in page %d "
"reading from %d ecc: corrected=%u failed=%u\n",
diff --git a/drivers/mtd/tests/mtd_nandecctest.c b/drivers/mtd/tests/mtd_nandecctest.c
index c4f271314f52..1c7201b0f372 100644
--- a/drivers/mtd/tests/mtd_nandecctest.c
+++ b/drivers/mtd/tests/mtd_nandecctest.c
@@ -47,7 +47,7 @@ struct nand_ecc_test {
static void single_bit_error_data(void *error_data, void *correct_data,
size_t size)
{
- unsigned int offset = prandom_u32() % (size * BITS_PER_BYTE);
+ unsigned int offset = prandom_u32_max(size * BITS_PER_BYTE);

memcpy(error_data, correct_data, size);
__change_bit_le(offset, error_data);
@@ -58,9 +58,9 @@ static void double_bit_error_data(void *error_data, void *correct_data,
{
unsigned int offset[2];

- offset[0] = prandom_u32() % (size * BITS_PER_BYTE);
+ offset[0] = prandom_u32_max(size * BITS_PER_BYTE);
do {
- offset[1] = prandom_u32() % (size * BITS_PER_BYTE);
+ offset[1] = prandom_u32_max(size * BITS_PER_BYTE);
} while (offset[0] == offset[1]);

memcpy(error_data, correct_data, size);
@@ -71,7 +71,7 @@ static void double_bit_error_data(void *error_data, void *correct_data,

static unsigned int random_ecc_bit(size_t size)
{
- unsigned int offset = prandom_u32() % (3 * BITS_PER_BYTE);
+ unsigned int offset = prandom_u32_max(3 * BITS_PER_BYTE);

if (size == 256) {
/*
@@ -79,7 +79,7 @@ static unsigned int random_ecc_bit(size_t size)
* and 17th bit) in ECC code for 256 byte data block
*/
while (offset == 16 || offset == 17)
- offset = prandom_u32() % (3 * BITS_PER_BYTE);
+ offset = prandom_u32_max(3 * BITS_PER_BYTE);
}

return offset;
diff --git a/drivers/mtd/tests/stresstest.c b/drivers/mtd/tests/stresstest.c
index cb29c8c1b370..d2faaca7f19d 100644
--- a/drivers/mtd/tests/stresstest.c
+++ b/drivers/mtd/tests/stresstest.c
@@ -45,9 +45,8 @@ static int rand_eb(void)
unsigned int eb;

again:
- eb = prandom_u32();
/* Read or write up 2 eraseblocks at a time - hence 'ebcnt - 1' */
- eb %= (ebcnt - 1);
+ eb = prandom_u32_max(ebcnt - 1);
if (bbt[eb])
goto again;
return eb;
@@ -55,20 +54,12 @@ static int rand_eb(void)

static int rand_offs(void)
{
- unsigned int offs;
-
- offs = prandom_u32();
- offs %= bufsize;
- return offs;
+ return prandom_u32_max(bufsize);
}

static int rand_len(int offs)
{
- unsigned int len;
-
- len = prandom_u32();
- len %= (bufsize - offs);
- return len;
+ return prandom_u32_max(bufsize - offs);
}

static int do_read(void)
@@ -127,7 +118,7 @@ static int do_write(void)

static int do_operation(void)
{
- if (prandom_u32() & 1)
+ if (prandom_u32_max(2))
return do_read();
else
return do_write();
diff --git a/drivers/mtd/ubi/debug.c b/drivers/mtd/ubi/debug.c
index 31d427ee191a..908d0e088557 100644
--- a/drivers/mtd/ubi/debug.c
+++ b/drivers/mtd/ubi/debug.c
@@ -590,7 +590,7 @@ int ubi_dbg_power_cut(struct ubi_device *ubi, int caller)

if (ubi->dbg.power_cut_max > ubi->dbg.power_cut_min) {
range = ubi->dbg.power_cut_max - ubi->dbg.power_cut_min;
- ubi->dbg.power_cut_counter += prandom_u32() % range;
+ ubi->dbg.power_cut_counter += prandom_u32_max(range);
}
return 0;
}
diff --git a/drivers/mtd/ubi/debug.h b/drivers/mtd/ubi/debug.h
index 118248a5d7d4..4236c799a47c 100644
--- a/drivers/mtd/ubi/debug.h
+++ b/drivers/mtd/ubi/debug.h
@@ -73,7 +73,7 @@ static inline int ubi_dbg_is_bgt_disabled(const struct ubi_device *ubi)
static inline int ubi_dbg_is_bitflip(const struct ubi_device *ubi)
{
if (ubi->dbg.emulate_bitflips)
- return !(prandom_u32() % 200);
+ return !(prandom_u32_max(200));
return 0;
}

@@ -87,7 +87,7 @@ static inline int ubi_dbg_is_bitflip(const struct ubi_device *ubi)
static inline int ubi_dbg_is_write_failure(const struct ubi_device *ubi)
{
if (ubi->dbg.emulate_io_failures)
- return !(prandom_u32() % 500);
+ return !(prandom_u32_max(500));
return 0;
}

@@ -101,7 +101,7 @@ static inline int ubi_dbg_is_write_failure(const struct ubi_device *ubi)
static inline int ubi_dbg_is_erase_failure(const struct ubi_device *ubi)
{
if (ubi->dbg.emulate_io_failures)
- return !(prandom_u32() % 400);
+ return !(prandom_u32_max(400));
return 0;
}

diff --git a/drivers/net/ethernet/broadcom/cnic.c b/drivers/net/ethernet/broadcom/cnic.c
index e86503d97f32..f597b313acaa 100644
--- a/drivers/net/ethernet/broadcom/cnic.c
+++ b/drivers/net/ethernet/broadcom/cnic.c
@@ -4105,8 +4105,7 @@ static int cnic_cm_alloc_mem(struct cnic_dev *dev)
for (i = 0; i < MAX_CM_SK_TBL_SZ; i++)
atomic_set(&cp->csk_tbl[i].ref_count, 0);

- port_id = prandom_u32();
- port_id %= CNIC_LOCAL_PORT_RANGE;
+ port_id = prandom_u32_max(CNIC_LOCAL_PORT_RANGE);
if (cnic_init_id_tbl(&cp->csk_port_tbl, CNIC_LOCAL_PORT_RANGE,
CNIC_LOCAL_PORT_MIN, port_id)) {
cnic_cm_free_mem(dev);
diff --git a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_io.c b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_io.c
index 539992dad8ba..a4256087ac82 100644
--- a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_io.c
+++ b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_io.c
@@ -919,8 +919,8 @@ static int csk_wait_memory(struct chtls_dev *cdev,
current_timeo = *timeo_p;
noblock = (*timeo_p ? false : true);
if (csk_mem_free(cdev, sk)) {
- current_timeo = (prandom_u32() % (HZ / 5)) + 2;
- vm_wait = (prandom_u32() % (HZ / 5)) + 2;
+ current_timeo = prandom_u32_max(HZ / 5) + 2;
+ vm_wait = prandom_u32_max(HZ / 5) + 2;
}

add_wait_queue(sk_sleep(sk), &wait);
diff --git a/drivers/net/hamradio/baycom_epp.c b/drivers/net/hamradio/baycom_epp.c
index 3e69079ed694..7df78a721b04 100644
--- a/drivers/net/hamradio/baycom_epp.c
+++ b/drivers/net/hamradio/baycom_epp.c
@@ -438,7 +438,7 @@ static int transmit(struct baycom_state *bc, int cnt, unsigned char stat)
if ((--bc->hdlctx.slotcnt) > 0)
return 0;
bc->hdlctx.slotcnt = bc->ch_params.slottime;
- if ((prandom_u32() % 256) > bc->ch_params.ppersist)
+ if (prandom_u32_max(256) > bc->ch_params.ppersist)
return 0;
}
}
diff --git a/drivers/net/hamradio/hdlcdrv.c b/drivers/net/hamradio/hdlcdrv.c
index 8297411e87ea..360d041a62c4 100644
--- a/drivers/net/hamradio/hdlcdrv.c
+++ b/drivers/net/hamradio/hdlcdrv.c
@@ -377,7 +377,7 @@ void hdlcdrv_arbitrate(struct net_device *dev, struct hdlcdrv_state *s)
if ((--s->hdlctx.slotcnt) > 0)
return;
s->hdlctx.slotcnt = s->ch_params.slottime;
- if ((prandom_u32() % 256) > s->ch_params.ppersist)
+ if (prandom_u32_max(256) > s->ch_params.ppersist)
return;
start_tx(dev, s);
}
diff --git a/drivers/net/hamradio/yam.c b/drivers/net/hamradio/yam.c
index 980f2be32f05..97a6cc5c7ae8 100644
--- a/drivers/net/hamradio/yam.c
+++ b/drivers/net/hamradio/yam.c
@@ -626,7 +626,7 @@ static void yam_arbitrate(struct net_device *dev)
yp->slotcnt = yp->slot / 10;

/* is random > persist ? */
- if ((prandom_u32() % 256) > yp->pers)
+ if (prandom_u32_max(256) > yp->pers)
return;

yam_start_tx(dev, yp);
diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
index 59fe356942b5..2a7108361246 100644
--- a/drivers/net/phy/at803x.c
+++ b/drivers/net/phy/at803x.c
@@ -1732,7 +1732,7 @@ static int qca808x_phy_fast_retrain_config(struct phy_device *phydev)

static int qca808x_phy_ms_random_seed_set(struct phy_device *phydev)
{
- u16 seed_value = (prandom_u32() % QCA808X_MASTER_SLAVE_SEED_RANGE);
+ u16 seed_value = prandom_u32_max(QCA808X_MASTER_SLAVE_SEED_RANGE);

return at803x_debug_reg_mask(phydev, QCA808X_PHY_DEBUG_LOCAL_SEED,
QCA808X_MASTER_SLAVE_SEED_CFG,
diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
index 479041f070f9..10d9d9c63b28 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
@@ -1128,7 +1128,7 @@ static void brcmf_p2p_afx_handler(struct work_struct *work)
if (afx_hdl->is_listen && afx_hdl->my_listen_chan)
/* 100ms ~ 300ms */
err = brcmf_p2p_discover_listen(p2p, afx_hdl->my_listen_chan,
- 100 * (1 + prandom_u32() % 3));
+ 100 * (1 + prandom_u32_max(3)));
else
err = brcmf_p2p_act_frm_search(p2p, afx_hdl->peer_listen_chan);

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c b/drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c
index ed586e6d7d64..de0c545d50fd 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c
@@ -1099,7 +1099,7 @@ static void iwl_mvm_mac_ctxt_cmd_fill_ap(struct iwl_mvm *mvm,
iwl_mvm_mac_ap_iterator, &data);

if (data.beacon_device_ts) {
- u32 rand = (prandom_u32() % (64 - 36)) + 36;
+ u32 rand = prandom_u32_max(64 - 36) + 36;
mvmvif->ap_beacon_time = data.beacon_device_ts +
ieee80211_tu_to_usec(data.beacon_int * rand /
100);
diff --git a/drivers/scsi/fcoe/fcoe_ctlr.c b/drivers/scsi/fcoe/fcoe_ctlr.c
index 39e16eab47aa..ddc048069af2 100644
--- a/drivers/scsi/fcoe/fcoe_ctlr.c
+++ b/drivers/scsi/fcoe/fcoe_ctlr.c
@@ -2233,7 +2233,7 @@ static void fcoe_ctlr_vn_restart(struct fcoe_ctlr *fip)

if (fip->probe_tries < FIP_VN_RLIM_COUNT) {
fip->probe_tries++;
- wait = prandom_u32() % FIP_VN_PROBE_WAIT;
+ wait = prandom_u32_max(FIP_VN_PROBE_WAIT);
} else
wait = FIP_VN_RLIM_INT;
mod_timer(&fip->timer, jiffies + msecs_to_jiffies(wait));
@@ -3125,7 +3125,7 @@ static void fcoe_ctlr_vn_timeout(struct fcoe_ctlr *fip)
fcoe_all_vn2vn, 0);
fip->port_ka_time = jiffies +
msecs_to_jiffies(FIP_VN_BEACON_INT +
- (prandom_u32() % FIP_VN_BEACON_FUZZ));
+ prandom_u32_max(FIP_VN_BEACON_FUZZ));
}
if (time_before(fip->port_ka_time, next_time))
next_time = fip->port_ka_time;
diff --git a/drivers/scsi/qedi/qedi_main.c b/drivers/scsi/qedi/qedi_main.c
index cecfb2cb4c7b..df2fe7bd26d1 100644
--- a/drivers/scsi/qedi/qedi_main.c
+++ b/drivers/scsi/qedi/qedi_main.c
@@ -618,7 +618,7 @@ static int qedi_cm_alloc_mem(struct qedi_ctx *qedi)
sizeof(struct qedi_endpoint *)), GFP_KERNEL);
if (!qedi->ep_tbl)
return -ENOMEM;
- port_id = prandom_u32() % QEDI_LOCAL_PORT_RANGE;
+ port_id = prandom_u32_max(QEDI_LOCAL_PORT_RANGE);
if (qedi_init_id_tbl(&qedi->lcl_port_tbl, QEDI_LOCAL_PORT_RANGE,
QEDI_LOCAL_PORT_MIN, port_id)) {
qedi_cm_free_mem(qedi);
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 42351d7a0dd6..f0c6e7e7b92b 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -362,7 +362,7 @@ static int ceph_fill_fragtree(struct inode *inode,
if (nsplits != ci->i_fragtree_nsplits) {
update = true;
} else if (nsplits) {
- i = prandom_u32() % nsplits;
+ i = prandom_u32_max(nsplits);
id = le32_to_cpu(fragtree->splits[i].frag);
if (!__ceph_find_frag(ci, id))
update = true;
diff --git a/fs/ceph/mdsmap.c b/fs/ceph/mdsmap.c
index 8d0a6d2c2da4..3fbabc98e1f7 100644
--- a/fs/ceph/mdsmap.c
+++ b/fs/ceph/mdsmap.c
@@ -29,7 +29,7 @@ static int __mdsmap_get_random_mds(struct ceph_mdsmap *m, bool ignore_laggy)
return -1;

/* pick */
- n = prandom_u32() % n;
+ n = prandom_u32_max(n);
for (j = 0, i = 0; i < m->possible_max_rank; i++) {
if (CEPH_MDS_IS_READY(i, ignore_laggy))
j++;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 9a66abcca1a8..4af351320075 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3811,8 +3811,7 @@ static int ext4_lazyinit_thread(void *arg)
}
if (!progress) {
elr->lr_next_sched = jiffies +
- (prandom_u32()
- % (EXT4_DEF_LI_MAX_START_DELAY * HZ));
+ prandom_u32_max(EXT4_DEF_LI_MAX_START_DELAY * HZ);
}
if (time_before(elr->lr_next_sched, next_wakeup))
next_wakeup = elr->lr_next_sched;
@@ -3959,8 +3958,8 @@ static struct ext4_li_request *ext4_li_request_new(struct super_block *sb,
* spread the inode table initialization requests
* better.
*/
- elr->lr_next_sched = jiffies + (prandom_u32() %
- (EXT4_DEF_LI_MAX_START_DELAY * HZ));
+ elr->lr_next_sched = jiffies + prandom_u32_max(
+ EXT4_DEF_LI_MAX_START_DELAY * HZ);
return elr;
}

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 6da21d405ce1..2c5fd1db3a3e 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -285,7 +285,7 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type,

/* let's select beginning hot/small space first in no_heap mode*/
if (f2fs_need_rand_seg(sbi))
- p->offset = prandom_u32() % (MAIN_SECS(sbi) * sbi->segs_per_sec);
+ p->offset = prandom_u32_max(MAIN_SECS(sbi) * sbi->segs_per_sec);
else if (test_opt(sbi, NOHEAP) &&
(type == CURSEG_HOT_DATA || IS_NODESEG(type)))
p->offset = 0;
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 0de21f82d7bc..507f77f839f3 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -2535,7 +2535,7 @@ static unsigned int __get_next_segno(struct f2fs_sb_info *sbi, int type)

sanity_check_seg_type(sbi, seg_type);
if (f2fs_need_rand_seg(sbi))
- return prandom_u32() % (MAIN_SECS(sbi) * sbi->segs_per_sec);
+ return prandom_u32_max(MAIN_SECS(sbi) * sbi->segs_per_sec);

/* if segs_per_sec is large than 1, we need to keep original policy. */
if (__is_large_section(sbi))
@@ -2589,7 +2589,7 @@ static void new_curseg(struct f2fs_sb_info *sbi, int type, bool new_sec)
curseg->alloc_type = LFS;
if (F2FS_OPTION(sbi).fs_mode == FS_MODE_FRAGMENT_BLK)
curseg->fragment_remained_chunk =
- prandom_u32() % sbi->max_fragment_chunk + 1;
+ prandom_u32_max(sbi->max_fragment_chunk) + 1;
}

static int __next_free_blkoff(struct f2fs_sb_info *sbi,
@@ -2626,9 +2626,9 @@ static void __refresh_next_blkoff(struct f2fs_sb_info *sbi,
/* To allocate block chunks in different sizes, use random number */
if (--seg->fragment_remained_chunk <= 0) {
seg->fragment_remained_chunk =
- prandom_u32() % sbi->max_fragment_chunk + 1;
+ prandom_u32_max(sbi->max_fragment_chunk) + 1;
seg->next_blkoff +=
- prandom_u32() % sbi->max_fragment_hole + 1;
+ prandom_u32_max(sbi->max_fragment_hole) + 1;
}
}
}
diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c
index fc718f6178f2..f4d3b568aa64 100644
--- a/fs/ubifs/debug.c
+++ b/fs/ubifs/debug.c
@@ -2467,7 +2467,7 @@ int dbg_check_nondata_nodes_order(struct ubifs_info *c, struct list_head *head)

static inline int chance(unsigned int n, unsigned int out_of)
{
- return !!((prandom_u32() % out_of) + 1 <= n);
+ return !!(prandom_u32_max(out_of) + 1 <= n);

}

@@ -2485,13 +2485,13 @@ static int power_cut_emulated(struct ubifs_info *c, int lnum, int write)
if (chance(1, 2)) {
d->pc_delay = 1;
/* Fail within 1 minute */
- delay = prandom_u32() % 60000;
+ delay = prandom_u32_max(60000);
d->pc_timeout = jiffies;
d->pc_timeout += msecs_to_jiffies(delay);
ubifs_warn(c, "failing after %lums", delay);
} else {
d->pc_delay = 2;
- delay = prandom_u32() % 10000;
+ delay = prandom_u32_max(10000);
/* Fail within 10000 operations */
d->pc_cnt_max = delay;
ubifs_warn(c, "failing after %lu calls", delay);
@@ -2571,7 +2571,7 @@ static int corrupt_data(const struct ubifs_info *c, const void *buf,
unsigned int from, to, ffs = chance(1, 2);
unsigned char *p = (void *)buf;

- from = prandom_u32() % len;
+ from = prandom_u32_max(len);
/* Corruption span max to end of write unit */
to = min(len, ALIGN(from + 1, c->max_write_size));

diff --git a/fs/ubifs/lpt_commit.c b/fs/ubifs/lpt_commit.c
index d76a19e460cd..cfbc31f709f4 100644
--- a/fs/ubifs/lpt_commit.c
+++ b/fs/ubifs/lpt_commit.c
@@ -1970,28 +1970,28 @@ static int dbg_populate_lsave(struct ubifs_info *c)

if (!dbg_is_chk_gen(c))
return 0;
- if (prandom_u32() & 3)
+ if (prandom_u32_max(4))
return 0;

for (i = 0; i < c->lsave_cnt; i++)
c->lsave[i] = c->main_first;

list_for_each_entry(lprops, &c->empty_list, list)
- c->lsave[prandom_u32() % c->lsave_cnt] = lprops->lnum;
+ c->lsave[prandom_u32_max(c->lsave_cnt)] = lprops->lnum;
list_for_each_entry(lprops, &c->freeable_list, list)
- c->lsave[prandom_u32() % c->lsave_cnt] = lprops->lnum;
+ c->lsave[prandom_u32_max(c->lsave_cnt)] = lprops->lnum;
list_for_each_entry(lprops, &c->frdi_idx_list, list)
- c->lsave[prandom_u32() % c->lsave_cnt] = lprops->lnum;
+ c->lsave[prandom_u32_max(c->lsave_cnt)] = lprops->lnum;

heap = &c->lpt_heap[LPROPS_DIRTY_IDX - 1];
for (i = 0; i < heap->cnt; i++)
- c->lsave[prandom_u32() % c->lsave_cnt] = heap->arr[i]->lnum;
+ c->lsave[prandom_u32_max(c->lsave_cnt)] = heap->arr[i]->lnum;
heap = &c->lpt_heap[LPROPS_DIRTY - 1];
for (i = 0; i < heap->cnt; i++)
- c->lsave[prandom_u32() % c->lsave_cnt] = heap->arr[i]->lnum;
+ c->lsave[prandom_u32_max(c->lsave_cnt)] = heap->arr[i]->lnum;
heap = &c->lpt_heap[LPROPS_FREE - 1];
for (i = 0; i < heap->cnt; i++)
- c->lsave[prandom_u32() % c->lsave_cnt] = heap->arr[i]->lnum;
+ c->lsave[prandom_u32_max(c->lsave_cnt)] = heap->arr[i]->lnum;

return 1;
}
diff --git a/fs/ubifs/tnc_commit.c b/fs/ubifs/tnc_commit.c
index 58c92c96ecef..01362ad5f804 100644
--- a/fs/ubifs/tnc_commit.c
+++ b/fs/ubifs/tnc_commit.c
@@ -700,7 +700,7 @@ static int alloc_idx_lebs(struct ubifs_info *c, int cnt)
c->ilebs[c->ileb_cnt++] = lnum;
dbg_cmt("LEB %d", lnum);
}
- if (dbg_is_chk_index(c) && !(prandom_u32() & 7))
+ if (dbg_is_chk_index(c) && !prandom_u32_max(8))
return -ENOSPC;
return 0;
}
diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index e2bdf089c0a3..6261599bb389 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -1520,7 +1520,7 @@ xfs_alloc_ag_vextent_lastblock(

#ifdef DEBUG
/* Randomly don't execute the first algorithm. */
- if (prandom_u32() & 1)
+ if (prandom_u32_max(2))
return 0;
#endif

diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
index 6cdfd64bc56b..7838b31126e2 100644
--- a/fs/xfs/libxfs/xfs_ialloc.c
+++ b/fs/xfs/libxfs/xfs_ialloc.c
@@ -636,7 +636,7 @@ xfs_ialloc_ag_alloc(
/* randomly do sparse inode allocations */
if (xfs_has_sparseinodes(tp->t_mountp) &&
igeo->ialloc_min_blks < igeo->ialloc_blks)
- do_sparse = prandom_u32() & 1;
+ do_sparse = prandom_u32_max(2);
#endif

/*
diff --git a/fs/xfs/xfs_error.c b/fs/xfs/xfs_error.c
index 296faa41d81d..7db588ed0be5 100644
--- a/fs/xfs/xfs_error.c
+++ b/fs/xfs/xfs_error.c
@@ -274,7 +274,7 @@ xfs_errortag_test(

ASSERT(error_tag < XFS_ERRTAG_MAX);
randfactor = mp->m_errortag[error_tag];
- if (!randfactor || prandom_u32() % randfactor)
+ if (!randfactor || prandom_u32_max(randfactor))
return false;

xfs_warn_ratelimited(mp,
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index cee5da1e54c4..8058bec87ace 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -310,7 +310,7 @@ static void clocksource_verify_choose_cpus(void)
* CPUs that are currently online.
*/
for (i = 1; i < n; i++) {
- cpu = prandom_u32() % nr_cpu_ids;
+ cpu = prandom_u32_max(nr_cpu_ids);
cpu = cpumask_next(cpu - 1, cpu_online_mask);
if (cpu >= nr_cpu_ids)
cpu = cpumask_first(cpu_online_mask);
diff --git a/lib/fault-inject.c b/lib/fault-inject.c
index 423784d9c058..96e092de5b72 100644
--- a/lib/fault-inject.c
+++ b/lib/fault-inject.c
@@ -139,7 +139,7 @@ bool should_fail(struct fault_attr *attr, ssize_t size)
return false;
}

- if (attr->probability <= prandom_u32() % 100)
+ if (attr->probability <= prandom_u32_max(100))
return false;

if (!fail_stacktrace(attr))
diff --git a/lib/find_bit_benchmark.c b/lib/find_bit_benchmark.c
index db904b57d4b8..1a6466c64bb6 100644
--- a/lib/find_bit_benchmark.c
+++ b/lib/find_bit_benchmark.c
@@ -157,8 +157,8 @@ static int __init find_bit_test(void)
bitmap_zero(bitmap2, BITMAP_LEN);

while (nbits--) {
- __set_bit(prandom_u32() % BITMAP_LEN, bitmap);
- __set_bit(prandom_u32() % BITMAP_LEN, bitmap2);
+ __set_bit(prandom_u32_max(BITMAP_LEN), bitmap);
+ __set_bit(prandom_u32_max(BITMAP_LEN), bitmap2);
}

test_find_next_bit(bitmap, BITMAP_LEN);
diff --git a/lib/reed_solomon/test_rslib.c b/lib/reed_solomon/test_rslib.c
index d9d1c33aebda..4d241bdc88aa 100644
--- a/lib/reed_solomon/test_rslib.c
+++ b/lib/reed_solomon/test_rslib.c
@@ -183,7 +183,7 @@ static int get_rcw_we(struct rs_control *rs, struct wspace *ws,

do {
/* Must not choose the same location twice */
- errloc = prandom_u32() % len;
+ errloc = prandom_u32_max(len);
} while (errlocs[errloc] != 0);

errlocs[errloc] = 1;
@@ -194,12 +194,12 @@ static int get_rcw_we(struct rs_control *rs, struct wspace *ws,
for (i = 0; i < eras; i++) {
do {
/* Must not choose the same location twice */
- errloc = prandom_u32() % len;
+ errloc = prandom_u32_max(len);
} while (errlocs[errloc] != 0);

derrlocs[i] = errloc;

- if (ewsc && (prandom_u32() & 1)) {
+ if (ewsc && prandom_u32_max(2)) {
/* Erasure with the symbol intact */
errlocs[errloc] = 2;
} else {
diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index 29eb0484215a..ef0661504561 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -21,7 +21,7 @@ static int init_alloc_hint(struct sbitmap *sb, gfp_t flags)
int i;

for_each_possible_cpu(i)
- *per_cpu_ptr(sb->alloc_hint, i) = prandom_u32() % depth;
+ *per_cpu_ptr(sb->alloc_hint, i) = prandom_u32_max(depth);
}
return 0;
}
@@ -33,7 +33,7 @@ static inline unsigned update_alloc_hint_before_get(struct sbitmap *sb,

hint = this_cpu_read(*sb->alloc_hint);
if (unlikely(hint >= depth)) {
- hint = depth ? prandom_u32() % depth : 0;
+ hint = depth ? prandom_u32_max(depth) : 0;
this_cpu_write(*sb->alloc_hint, hint);
}

diff --git a/lib/test_list_sort.c b/lib/test_list_sort.c
index ade7a1ea0c8e..19ff229b9c3a 100644
--- a/lib/test_list_sort.c
+++ b/lib/test_list_sort.c
@@ -71,7 +71,7 @@ static void list_sort_test(struct kunit *test)
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, el);

/* force some equivalencies */
- el->value = prandom_u32() % (TEST_LIST_LEN / 3);
+ el->value = prandom_u32_max(TEST_LIST_LEN / 3);
el->serial = i;
el->poison1 = TEST_POISON1;
el->poison2 = TEST_POISON2;
diff --git a/lib/test_vmalloc.c b/lib/test_vmalloc.c
index 4f2f2d1bac56..56ffaa8dd3f6 100644
--- a/lib/test_vmalloc.c
+++ b/lib/test_vmalloc.c
@@ -151,9 +151,7 @@ static int random_size_alloc_test(void)
int i;

for (i = 0; i < test_loop_count; i++) {
- n = prandom_u32();
- n = (n % 100) + 1;
-
+ n = prandom_u32_max(n % 100) + 1;
p = vmalloc(n * PAGE_SIZE);

if (!p)
@@ -293,16 +291,12 @@ pcpu_alloc_test(void)
return -1;

for (i = 0; i < 35000; i++) {
- unsigned int r;
-
- r = prandom_u32();
- size = (r % (PAGE_SIZE / 4)) + 1;
+ size = prandom_u32_max(PAGE_SIZE / 4) + 1;

/*
* Maximum PAGE_SIZE
*/
- r = prandom_u32();
- align = 1 << ((r % 11) + 1);
+ align = 1 << (prandom_u32_max(11) + 1);

pcpu[i] = __alloc_percpu(size, align);
if (!pcpu[i])
@@ -393,14 +387,11 @@ static struct test_driver {

static void shuffle_array(int *arr, int n)
{
- unsigned int rnd;
int i, j;

for (i = n - 1; i > 0; i--) {
- rnd = prandom_u32();
-
/* Cut the range. */
- j = rnd % i;
+ j = prandom_u32_max(i);

/* Swap indexes. */
swap(arr[i], arr[j]);
diff --git a/net/ceph/mon_client.c b/net/ceph/mon_client.c
index 6a6898ee4049..db60217f911b 100644
--- a/net/ceph/mon_client.c
+++ b/net/ceph/mon_client.c
@@ -222,7 +222,7 @@ static void pick_new_mon(struct ceph_mon_client *monc)
max--;
}

- n = prandom_u32() % max;
+ n = prandom_u32_max(max);
if (o >= 0 && n >= o)
n++;

diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 87b883c7bfd6..4e4f1e4bc265 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -1479,7 +1479,7 @@ static bool target_should_be_paused(struct ceph_osd_client *osdc,

static int pick_random_replica(const struct ceph_osds *acting)
{
- int i = prandom_u32() % acting->size;
+ int i = prandom_u32_max(acting->size);

dout("%s picked osd%d, primary osd%d\n", __func__,
acting->osds[i], acting->primary);
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 78cc8fb68814..85d497cb58d8 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -111,7 +111,7 @@ static void neigh_cleanup_and_release(struct neighbour *neigh)

unsigned long neigh_rand_reach_time(unsigned long base)
{
- return base ? (prandom_u32() % base) + (base >> 1) : 0;
+ return base ? prandom_u32_max(base) + (base >> 1) : 0;
}
EXPORT_SYMBOL(neigh_rand_reach_time);

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 88906ba6d9a7..5ca4f953034c 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -2324,7 +2324,7 @@ static inline int f_pick(struct pktgen_dev *pkt_dev)
pkt_dev->curfl = 0; /*reset */
}
} else {
- flow = prandom_u32() % pkt_dev->cflows;
+ flow = prandom_u32_max(pkt_dev->cflows);
pkt_dev->curfl = flow;

if (pkt_dev->flows[flow].count > pkt_dev->lflow) {
@@ -2380,10 +2380,9 @@ static void set_cur_queue_map(struct pktgen_dev *pkt_dev)
else if (pkt_dev->queue_map_min <= pkt_dev->queue_map_max) {
__u16 t;
if (pkt_dev->flags & F_QUEUE_MAP_RND) {
- t = prandom_u32() %
- (pkt_dev->queue_map_max -
- pkt_dev->queue_map_min + 1)
- + pkt_dev->queue_map_min;
+ t = prandom_u32_max(pkt_dev->queue_map_max -
+ pkt_dev->queue_map_min + 1) +
+ pkt_dev->queue_map_min;
} else {
t = pkt_dev->cur_queue_map + 1;
if (t > pkt_dev->queue_map_max)
@@ -2412,7 +2411,7 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
__u32 tmp;

if (pkt_dev->flags & F_MACSRC_RND)
- mc = prandom_u32() % pkt_dev->src_mac_count;
+ mc = prandom_u32_max(pkt_dev->src_mac_count);
else {
mc = pkt_dev->cur_src_mac_offset++;
if (pkt_dev->cur_src_mac_offset >=
@@ -2438,7 +2437,7 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
__u32 tmp;

if (pkt_dev->flags & F_MACDST_RND)
- mc = prandom_u32() % pkt_dev->dst_mac_count;
+ mc = prandom_u32_max(pkt_dev->dst_mac_count);

else {
mc = pkt_dev->cur_dst_mac_offset++;
@@ -2470,18 +2469,18 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
}

if ((pkt_dev->flags & F_VID_RND) && (pkt_dev->vlan_id != 0xffff)) {
- pkt_dev->vlan_id = prandom_u32() & (4096 - 1);
+ pkt_dev->vlan_id = prandom_u32_max(4096);
}

if ((pkt_dev->flags & F_SVID_RND) && (pkt_dev->svlan_id != 0xffff)) {
- pkt_dev->svlan_id = prandom_u32() & (4096 - 1);
+ pkt_dev->svlan_id = prandom_u32_max(4096);
}

if (pkt_dev->udp_src_min < pkt_dev->udp_src_max) {
if (pkt_dev->flags & F_UDPSRC_RND)
- pkt_dev->cur_udp_src = prandom_u32() %
- (pkt_dev->udp_src_max - pkt_dev->udp_src_min)
- + pkt_dev->udp_src_min;
+ pkt_dev->cur_udp_src = prandom_u32_max(
+ pkt_dev->udp_src_max - pkt_dev->udp_src_min) +
+ pkt_dev->udp_src_min;

else {
pkt_dev->cur_udp_src++;
@@ -2492,9 +2491,9 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)

if (pkt_dev->udp_dst_min < pkt_dev->udp_dst_max) {
if (pkt_dev->flags & F_UDPDST_RND) {
- pkt_dev->cur_udp_dst = prandom_u32() %
- (pkt_dev->udp_dst_max - pkt_dev->udp_dst_min)
- + pkt_dev->udp_dst_min;
+ pkt_dev->cur_udp_dst = prandom_u32_max(
+ pkt_dev->udp_dst_max - pkt_dev->udp_dst_min) +
+ pkt_dev->udp_dst_min;
} else {
pkt_dev->cur_udp_dst++;
if (pkt_dev->cur_udp_dst >= pkt_dev->udp_dst_max)
@@ -2509,7 +2508,7 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
if (imn < imx) {
__u32 t;
if (pkt_dev->flags & F_IPSRC_RND)
- t = prandom_u32() % (imx - imn) + imn;
+ t = prandom_u32_max(imx - imn) + imn;
else {
t = ntohl(pkt_dev->cur_saddr);
t++;
@@ -2531,8 +2530,8 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
if (pkt_dev->flags & F_IPDST_RND) {

do {
- t = prandom_u32() %
- (imx - imn) + imn;
+ t = prandom_u32_max(imx - imn) +
+ imn;
s = htonl(t);
} while (ipv4_is_loopback(s) ||
ipv4_is_multicast(s) ||
@@ -2579,9 +2578,9 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
if (pkt_dev->min_pkt_size < pkt_dev->max_pkt_size) {
__u32 t;
if (pkt_dev->flags & F_TXSIZE_RND) {
- t = prandom_u32() %
- (pkt_dev->max_pkt_size - pkt_dev->min_pkt_size)
- + pkt_dev->min_pkt_size;
+ t = prandom_u32_max(pkt_dev->max_pkt_size -
+ pkt_dev->min_pkt_size) +
+ pkt_dev->min_pkt_size;
} else {
t = pkt_dev->cur_pkt_size + 1;
if (t > pkt_dev->max_pkt_size)
@@ -2590,7 +2589,7 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
pkt_dev->cur_pkt_size = t;
} else if (pkt_dev->n_imix_entries > 0) {
struct imix_pkt *entry;
- __u32 t = prandom_u32() % IMIX_PRECISION;
+ __u32 t = prandom_u32_max(IMIX_PRECISION);
__u8 entry_index = pkt_dev->imix_distribution[t];

entry = &pkt_dev->imix_entries[entry_index];
diff --git a/net/core/stream.c b/net/core/stream.c
index ccc083cdef23..4780558ea314 100644
--- a/net/core/stream.c
+++ b/net/core/stream.c
@@ -123,7 +123,7 @@ int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
DEFINE_WAIT_FUNC(wait, woken_wake_function);

if (sk_stream_memory_free(sk))
- current_timeo = vm_wait = (prandom_u32() % (HZ / 5)) + 2;
+ current_timeo = vm_wait = prandom_u32_max(HZ / 5) + 2;

add_wait_queue(sk_sleep(sk), &wait);

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index e3ab0cb61624..9149e78beea5 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -213,7 +213,7 @@ static void igmp_stop_timer(struct ip_mc_list *im)
/* It must be called with locked im->lock */
static void igmp_start_timer(struct ip_mc_list *im, int max_delay)
{
- int tv = prandom_u32() % max_delay;
+ int tv = prandom_u32_max(max_delay);

im->tm_running = 1;
if (!mod_timer(&im->timer, jiffies+tv+2))
@@ -222,7 +222,7 @@ static void igmp_start_timer(struct ip_mc_list *im, int max_delay)

static void igmp_gq_start_timer(struct in_device *in_dev)
{
- int tv = prandom_u32() % in_dev->mr_maxdelay;
+ int tv = prandom_u32_max(in_dev->mr_maxdelay);
unsigned long exp = jiffies + tv + 2;

if (in_dev->mr_gq_running &&
@@ -236,7 +236,7 @@ static void igmp_gq_start_timer(struct in_device *in_dev)

static void igmp_ifc_start_timer(struct in_device *in_dev, int delay)
{
- int tv = prandom_u32() % delay;
+ int tv = prandom_u32_max(delay);

if (!mod_timer(&in_dev->mr_ifc_timer, jiffies+tv+2))
in_dev_hold(in_dev);
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index eb31c7158b39..0c3eab1347cd 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -223,7 +223,7 @@ inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int *
if (likely(remaining > 1))
remaining &= ~1U;

- offset = prandom_u32() % remaining;
+ offset = prandom_u32_max(remaining);
/* __inet_hash_connect() favors ports having @low parity
* We do the opposite to not pollute connect() users.
*/
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index b9d995b5ce24..9dc070f2018e 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -794,7 +794,7 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
* on low contention the randomness is maximal and on high contention
* it may be inexistent.
*/
- i = max_t(int, i, (prandom_u32() & 7) * 2);
+ i = max_t(int, i, prandom_u32_max(8) * 2);
WRITE_ONCE(table_perturb[index], READ_ONCE(table_perturb[index]) + i + 2);

/* Head lock still held and bh's disabled */
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 10ce86bf228e..417834b7169d 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -104,7 +104,7 @@ static inline u32 cstamp_delta(unsigned long cstamp)
static inline s32 rfc3315_s14_backoff_init(s32 irt)
{
/* multiply 'initial retransmission time' by 0.9 .. 1.1 */
- u64 tmp = (900000 + prandom_u32() % 200001) * (u64)irt;
+ u64 tmp = (900000 + prandom_u32_max(200001)) * (u64)irt;
do_div(tmp, 1000000);
return (s32)tmp;
}
@@ -112,11 +112,11 @@ static inline s32 rfc3315_s14_backoff_init(s32 irt)
static inline s32 rfc3315_s14_backoff_update(s32 rt, s32 mrt)
{
/* multiply 'retransmission timeout' by 1.9 .. 2.1 */
- u64 tmp = (1900000 + prandom_u32() % 200001) * (u64)rt;
+ u64 tmp = (1900000 + prandom_u32_max(200001)) * (u64)rt;
do_div(tmp, 1000000);
if ((s32)tmp > mrt) {
/* multiply 'maximum retransmission time' by 0.9 .. 1.1 */
- tmp = (900000 + prandom_u32() % 200001) * (u64)mrt;
+ tmp = (900000 + prandom_u32_max(200001)) * (u64)mrt;
do_div(tmp, 1000000);
}
return (s32)tmp;
@@ -3967,7 +3967,7 @@ static void addrconf_dad_kick(struct inet6_ifaddr *ifp)
if (ifp->flags & IFA_F_OPTIMISTIC)
rand_num = 0;
else
- rand_num = prandom_u32() % (idev->cnf.rtr_solicit_delay ? : 1);
+ rand_num = prandom_u32_max(idev->cnf.rtr_solicit_delay ?: 1);

nonce = 0;
if (idev->cnf.enhanced_dad ||
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 87c699d57b36..bf4f5edb3c3e 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1050,7 +1050,7 @@ bool ipv6_chk_mcast_addr(struct net_device *dev, const struct in6_addr *group,
/* called with mc_lock */
static void mld_gq_start_work(struct inet6_dev *idev)
{
- unsigned long tv = prandom_u32() % idev->mc_maxdelay;
+ unsigned long tv = prandom_u32_max(idev->mc_maxdelay);

idev->mc_gq_running = 1;
if (!mod_delayed_work(mld_wq, &idev->mc_gq_work, tv + 2))
@@ -1068,7 +1068,7 @@ static void mld_gq_stop_work(struct inet6_dev *idev)
/* called with mc_lock */
static void mld_ifc_start_work(struct inet6_dev *idev, unsigned long delay)
{
- unsigned long tv = prandom_u32() % delay;
+ unsigned long tv = prandom_u32_max(delay);

if (!mod_delayed_work(mld_wq, &idev->mc_ifc_work, tv + 2))
in6_dev_hold(idev);
@@ -1085,7 +1085,7 @@ static void mld_ifc_stop_work(struct inet6_dev *idev)
/* called with mc_lock */
static void mld_dad_start_work(struct inet6_dev *idev, unsigned long delay)
{
- unsigned long tv = prandom_u32() % delay;
+ unsigned long tv = prandom_u32_max(delay);

if (!mod_delayed_work(mld_wq, &idev->mc_dad_work, tv + 2))
in6_dev_hold(idev);
@@ -1130,7 +1130,7 @@ static void igmp6_group_queried(struct ifmcaddr6 *ma, unsigned long resptime)
}

if (delay >= resptime)
- delay = prandom_u32() % resptime;
+ delay = prandom_u32_max(resptime);

if (!mod_delayed_work(mld_wq, &ma->mca_work, delay))
refcount_inc(&ma->mca_refcnt);
@@ -2574,7 +2574,7 @@ static void igmp6_join_group(struct ifmcaddr6 *ma)

igmp6_send(&ma->mca_addr, ma->idev->dev, ICMPV6_MGM_REPORT);

- delay = prandom_u32() % unsolicited_report_interval(ma->idev);
+ delay = prandom_u32_max(unsolicited_report_interval(ma->idev));

if (cancel_delayed_work(&ma->mca_work)) {
refcount_dec(&ma->mca_refcnt);
diff --git a/net/netfilter/ipvs/ip_vs_twos.c b/net/netfilter/ipvs/ip_vs_twos.c
index acb55d8393ef..f2579fc9c75b 100644
--- a/net/netfilter/ipvs/ip_vs_twos.c
+++ b/net/netfilter/ipvs/ip_vs_twos.c
@@ -71,8 +71,8 @@ static struct ip_vs_dest *ip_vs_twos_schedule(struct ip_vs_service *svc,
* from 0 to total_weight
*/
total_weight += 1;
- rweight1 = prandom_u32() % total_weight;
- rweight2 = prandom_u32() % total_weight;
+ rweight1 = prandom_u32_max(total_weight);
+ rweight2 = prandom_u32_max(total_weight);

/* Pick two weighted servers */
list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 5cbe07116e04..331f80e12779 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1350,7 +1350,7 @@ static bool fanout_flow_is_huge(struct packet_sock *po, struct sk_buff *skb)
if (READ_ONCE(history[i]) == rxhash)
count++;

- victim = prandom_u32() % ROLLOVER_HLEN;
+ victim = prandom_u32_max(ROLLOVER_HLEN);

/* Avoid dirtying the cache line if possible */
if (READ_ONCE(history[victim]) != rxhash)
diff --git a/net/sched/act_gact.c b/net/sched/act_gact.c
index ac29d1065232..1accaedef54f 100644
--- a/net/sched/act_gact.c
+++ b/net/sched/act_gact.c
@@ -26,7 +26,7 @@ static struct tc_action_ops act_gact_ops;
static int gact_net_rand(struct tcf_gact *gact)
{
smp_rmb(); /* coupled with smp_wmb() in tcf_gact_init() */
- if (prandom_u32() % gact->tcfg_pval)
+ if (prandom_u32_max(gact->tcfg_pval))
return gact->tcf_action;
return gact->tcfg_paction;
}
diff --git a/net/sched/act_sample.c b/net/sched/act_sample.c
index 2f7f5e44d28c..55c9f961fb0f 100644
--- a/net/sched/act_sample.c
+++ b/net/sched/act_sample.c
@@ -169,7 +169,7 @@ static int tcf_sample_act(struct sk_buff *skb, const struct tc_action *a,
psample_group = rcu_dereference_bh(s->psample_group);

/* randomly sample packets according to rate */
- if (psample_group && (prandom_u32() % s->rate == 0)) {
+ if (psample_group && (prandom_u32_max(s->rate) == 0)) {
if (!skb_at_tc_ingress(skb)) {
md.in_ifindex = skb->skb_iif;
md.out_ifindex = skb->dev->ifindex;
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 5449ed114e40..3ca320f1a031 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -513,8 +513,8 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
goto finish_segs;
}

- skb->data[prandom_u32() % skb_headlen(skb)] ^=
- 1<<(prandom_u32() % 8);
+ skb->data[prandom_u32_max(skb_headlen(skb))] ^=
+ 1<<prandom_u32_max(8);
}

if (unlikely(sch->q.qlen >= sch->limit)) {
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 171f1a35d205..1e354ba44960 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -8319,7 +8319,7 @@ static int sctp_get_port_local(struct sock *sk, union sctp_addr *addr)

inet_get_local_port_range(net, &low, &high);
remaining = (high - low) + 1;
- rover = prandom_u32() % remaining + low;
+ rover = prandom_u32_max(remaining) + low;

do {
rover++;
diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index c3c693b51c94..f075a9fb5ccc 100644
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -677,7 +677,7 @@ static void cache_limit_defers(void)

/* Consider removing either the first or the last */
if (cache_defer_cnt > DFR_MAX) {
- if (prandom_u32() & 1)
+ if (prandom_u32_max(2))
discard = list_entry(cache_defer_list.next,
struct cache_deferred_req, recent);
else
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index e976007f4fd0..c2caee703d2c 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1619,7 +1619,7 @@ static int xs_get_random_port(void)
if (max < min)
return -EADDRINUSE;
range = max - min + 1;
- rand = (unsigned short) prandom_u32() % range;
+ rand = (unsigned short) prandom_u32_max(range);
return rand + min;
}

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index f1c3b8eb4b3d..e902b01ea3cb 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -3010,7 +3010,7 @@ static int tipc_sk_insert(struct tipc_sock *tsk)
struct net *net = sock_net(sk);
struct tipc_net *tn = net_generic(net, tipc_net_id);
u32 remaining = (TIPC_MAX_PORT - TIPC_MIN_PORT) + 1;
- u32 portid = prandom_u32() % remaining + TIPC_MIN_PORT;
+ u32 portid = prandom_u32_max(remaining) + TIPC_MIN_PORT;

while (remaining--) {
portid++;
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 91c32a3b6924..b213c89cfb8a 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -2072,7 +2072,7 @@ int xfrm_alloc_spi(struct xfrm_state *x, u32 low, u32 high)
} else {
u32 spi = 0;
for (h = 0; h < high-low+1; h++) {
- spi = low + prandom_u32()%(high-low+1);
+ spi = low + prandom_u32_max(high - low + 1);
x0 = xfrm_state_lookup(net, mark, &x->id.daddr, htonl(spi), x->id.proto, x->props.family);
if (x0 == NULL) {
newspi = htonl(spi);
--
2.37.3

2022-10-06 06:37:09

by Kees Cook

Subject: Re: [PATCH v1 0/5] treewide cleanup of random integer usage

On Wed, Oct 05, 2022 at 11:48:39PM +0200, Jason A. Donenfeld wrote:
> I've CC'd get_maintainers.pl, which is a pretty big list. Probably some
> portion of those are going to bounce, too, and everytime you reply to

The real problem is that replies may not reach the vger lists:

Subject: BOUNCE [email protected]: Header field too long (>8192)

But the originals somehow ended up on lore?

https://lore.kernel.org/lkml/[email protected]/

--
Kees Cook

2022-10-06 09:18:05

by Christoph Böhmwalder

Subject: Re: [PATCH v1 1/5] treewide: use prandom_u32_max() when possible

On 05.10.22 23:48, Jason A. Donenfeld wrote:
> Rather than incurring a division or requesting too many random bytes for
> the given range, use the prandom_u32_max() function, which only takes
> the minimum required bytes from the RNG and avoids divisions.
>
> Signed-off-by: Jason A. Donenfeld <[email protected]>
> ---
> arch/x86/mm/pat/cpa-test.c | 4 +-
> crypto/testmgr.c | 86 +++++++++----------
> drivers/block/drbd/drbd_receiver.c | 4 +-

For the drbd part:

Reviewed-by: Christoph Böhmwalder <[email protected]>

> drivers/infiniband/core/cma.c | 2 +-
> drivers/infiniband/hw/cxgb4/id_table.c | 4 +-
> drivers/infiniband/hw/hns/hns_roce_ah.c | 5 +-
> drivers/infiniband/ulp/rtrs/rtrs-clt.c | 3 +-
> drivers/mmc/core/core.c | 4 +-
> drivers/mmc/host/dw_mmc.c | 2 +-
> drivers/mtd/nand/raw/nandsim.c | 4 +-
> drivers/mtd/tests/mtd_nandecctest.c | 10 +--
> drivers/mtd/tests/stresstest.c | 17 +---
> drivers/mtd/ubi/debug.c | 2 +-
> drivers/mtd/ubi/debug.h | 6 +-
> drivers/net/ethernet/broadcom/cnic.c | 3 +-
> .../chelsio/inline_crypto/chtls/chtls_io.c | 4 +-
> drivers/net/hamradio/baycom_epp.c | 2 +-
> drivers/net/hamradio/hdlcdrv.c | 2 +-
> drivers/net/hamradio/yam.c | 2 +-
> drivers/net/phy/at803x.c | 2 +-
> .../broadcom/brcm80211/brcmfmac/p2p.c | 2 +-
> .../net/wireless/intel/iwlwifi/mvm/mac-ctxt.c | 2 +-
> drivers/scsi/fcoe/fcoe_ctlr.c | 4 +-
> drivers/scsi/qedi/qedi_main.c | 2 +-
> fs/ceph/inode.c | 2 +-
> fs/ceph/mdsmap.c | 2 +-
> fs/ext4/super.c | 7 +-
> fs/f2fs/gc.c | 2 +-
> fs/f2fs/segment.c | 8 +-
> fs/ubifs/debug.c | 8 +-
> fs/ubifs/lpt_commit.c | 14 +--
> fs/ubifs/tnc_commit.c | 2 +-
> fs/xfs/libxfs/xfs_alloc.c | 2 +-
> fs/xfs/libxfs/xfs_ialloc.c | 2 +-
> fs/xfs/xfs_error.c | 2 +-
> kernel/time/clocksource.c | 2 +-
> lib/fault-inject.c | 2 +-
> lib/find_bit_benchmark.c | 4 +-
> lib/reed_solomon/test_rslib.c | 6 +-
> lib/sbitmap.c | 4 +-
> lib/test_list_sort.c | 2 +-
> lib/test_vmalloc.c | 17 +---
> net/ceph/mon_client.c | 2 +-
> net/ceph/osd_client.c | 2 +-
> net/core/neighbour.c | 2 +-
> net/core/pktgen.c | 43 +++++-----
> net/core/stream.c | 2 +-
> net/ipv4/igmp.c | 6 +-
> net/ipv4/inet_connection_sock.c | 2 +-
> net/ipv4/inet_hashtables.c | 2 +-
> net/ipv6/addrconf.c | 8 +-
> net/ipv6/mcast.c | 10 +--
> net/netfilter/ipvs/ip_vs_twos.c | 4 +-
> net/packet/af_packet.c | 2 +-
> net/sched/act_gact.c | 2 +-
> net/sched/act_sample.c | 2 +-
> net/sched/sch_netem.c | 4 +-
> net/sctp/socket.c | 2 +-
> net/sunrpc/cache.c | 2 +-
> net/sunrpc/xprtsock.c | 2 +-
> net/tipc/socket.c | 2 +-
> net/xfrm/xfrm_state.c | 2 +-
> 62 files changed, 173 insertions(+), 196 deletions(-)
>
[...]
> diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
> index af4c7d65490b..d8b1417dc503 100644
> --- a/drivers/block/drbd/drbd_receiver.c
> +++ b/drivers/block/drbd/drbd_receiver.c
> @@ -781,7 +781,7 @@ static struct socket *drbd_wait_for_connect(struct drbd_connection *connection,
>
> timeo = connect_int * HZ;
> /* 28.5% random jitter */
> - timeo += (prandom_u32() & 1) ? timeo / 7 : -timeo / 7;
> + timeo += prandom_u32_max(2) ? timeo / 7 : -timeo / 7;
>
> err = wait_for_completion_interruptible_timeout(&ad->door_bell, timeo);
> if (err <= 0)
> @@ -1004,7 +1004,7 @@ static int conn_connect(struct drbd_connection *connection)
> drbd_warn(connection, "Error receiving initial packet\n");
> sock_release(s);
> randomize:
> - if (prandom_u32() & 1)
> + if (prandom_u32_max(2))
> goto retry;
> }
> }[...]

(Had to cut out most of the CC list because Google complains about "too many
recipients").

--
Christoph Böhmwalder
LINBIT | Keeping the Digital World Running
DRBD HA — Disaster Recovery — Software defined Storage

2022-10-06 13:40:30

by Jason A. Donenfeld

Subject: Re: [PATCH v1 0/5] treewide cleanup of random integer usage

On Thu, Oct 6, 2022 at 12:15 AM Kees Cook <[email protected]> wrote:
>
> On Wed, Oct 05, 2022 at 11:48:39PM +0200, Jason A. Donenfeld wrote:
> > I've CC'd get_maintainers.pl, which is a pretty big list. Probably some
> > portion of those are going to bounce, too, and everytime you reply to
>
> The real problem is that replies may not reach the vger lists:
>
> Subject: BOUNCE [email protected]: Header field too long (>8192)
>
> But the originals somehow ended up on lore?
>
> https://lore.kernel.org/lkml/[email protected]/

Heh, those aren't quite the originals. Same message IDs, but I did
evil things to get them on there.

v2 coming shortly to rectify this mess.

Jason

2022-10-06 13:53:48

by Toke Høiland-Jørgensen

Subject: Re: [PATCH v1 2/5] treewide: use get_random_{u8,u16}() when possible

"Jason A. Donenfeld" <[email protected]> writes:

> Rather than truncate a 32-bit value to a 16-bit value or an 8-bit value,
> simply use the get_random_{u8,u16}() functions, which are faster than
> wasting the additional bytes from a 32-bit value.
>
> Signed-off-by: Jason A. Donenfeld <[email protected]>
> ---
> crypto/testmgr.c | 8 ++++----
> drivers/media/common/v4l2-tpg/v4l2-tpg-core.c | 2 +-
> drivers/media/test-drivers/vivid/vivid-radio-rx.c | 4 ++--
> .../net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c | 2 +-
> drivers/net/hamradio/baycom_epp.c | 2 +-
> drivers/net/hamradio/hdlcdrv.c | 2 +-
> drivers/net/hamradio/yam.c | 2 +-
> drivers/net/wireguard/selftest/allowedips.c | 4 ++--
> drivers/scsi/lpfc/lpfc_hbadisc.c | 6 +++---
> lib/test_vmalloc.c | 2 +-
> net/dccp/ipv4.c | 4 ++--
> net/ipv4/datagram.c | 2 +-
> net/ipv4/ip_output.c | 2 +-
> net/ipv4/tcp_ipv4.c | 4 ++--
> net/mac80211/scan.c | 2 +-
> net/netfilter/nf_nat_core.c | 4 ++--
> net/sched/sch_cake.c | 6 +++---
> net/sched/sch_sfb.c | 2 +-
> net/sctp/socket.c | 2 +-
> 19 files changed, 31 insertions(+), 31 deletions(-)

For sch_cake:

Acked-by: Toke Høiland-Jørgensen <[email protected]>