Syzkaller reported the following issue:
=======================================
Too BIG xdp->frame_sz = 131072
WARNING: CPU: 0 PID: 5020 at net/core/filter.c:4121
____bpf_xdp_adjust_tail net/core/filter.c:4121 [inline]
WARNING: CPU: 0 PID: 5020 at net/core/filter.c:4121
bpf_xdp_adjust_tail+0x466/0xa10 net/core/filter.c:4103
...
Call Trace:
<TASK>
bpf_prog_4add87e5301a4105+0x1a/0x1c
__bpf_prog_run include/linux/filter.h:600 [inline]
bpf_prog_run_xdp include/linux/filter.h:775 [inline]
bpf_prog_run_generic_xdp+0x57e/0x11e0 net/core/dev.c:4721
netif_receive_generic_xdp net/core/dev.c:4807 [inline]
do_xdp_generic+0x35c/0x770 net/core/dev.c:4866
tun_get_user+0x2340/0x3ca0 drivers/net/tun.c:1919
tun_chr_write_iter+0xe8/0x210 drivers/net/tun.c:2043
call_write_iter include/linux/fs.h:1871 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x650/0xe40 fs/read_write.c:584
ksys_write+0x12f/0x250 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
xdp->frame_sz > PAGE_SIZE check was introduced in commit c8741e2bfe87
("xdp: Allow bpf_xdp_adjust_tail() to grow packet size"). But Jesper
Dangaard Brouer <[email protected]> noted that after introducing the
xdp_init_buff() which all XDP driver use - it's safe to remove this
check. The original intend was to catch cases where XDP drivers have
not been updated to use xdp.frame_sz, but that is not longer a concern
(since xdp_init_buff).
Running the initial syzkaller repro it was discovered that the
contiguous physical memory allocation is used for both xdp paths in
tun_get_user(), e.g. tun_build_skb() and tun_alloc_skb(). It was also
stated by Jesper Dangaard Brouer <[email protected]> that XDP can
work on higher order pages, as long as this is contiguous physical
memory (e.g. a page).
Reported-and-tested-by: [email protected]
Closes: https://lore.kernel.org/all/[email protected]/T/
Link: https://syzkaller.appspot.com/bug?extid=f817490f5bd20541b90a
Link: https://lore.kernel.org/all/[email protected]/T/
Fixes: 43b5169d8355 ("net, xdp: Introduce xdp_init_buff utility routine")
Signed-off-by: Andrew Kanner <[email protected]>
---
net/core/filter.c | 6 ------
1 file changed, 6 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index 06ba0e56e369..28a59596987a 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4116,12 +4116,6 @@ BPF_CALL_2(bpf_xdp_adjust_tail, struct xdp_buff *, xdp, int, offset)
if (unlikely(data_end > data_hard_end))
return -EINVAL;
- /* ALL drivers MUST init xdp->frame_sz, chicken check below */
- if (unlikely(xdp->frame_sz > PAGE_SIZE)) {
- WARN_ONCE(1, "Too BIG xdp->frame_sz = %d\n", xdp->frame_sz);
- return -EINVAL;
- }
-
if (unlikely(data_end < xdp->data + ETH_HLEN))
return -EINVAL;
--
2.39.3
On 02/08/2023 00.07, Andrew Kanner wrote:
> Syzkaller reported the following issue:
> =======================================
> Too BIG xdp->frame_sz = 131072
> WARNING: CPU: 0 PID: 5020 at net/core/filter.c:4121
> ____bpf_xdp_adjust_tail net/core/filter.c:4121 [inline]
> WARNING: CPU: 0 PID: 5020 at net/core/filter.c:4121
> bpf_xdp_adjust_tail+0x466/0xa10 net/core/filter.c:4103
> ...
> Call Trace:
> <TASK>
> bpf_prog_4add87e5301a4105+0x1a/0x1c
> __bpf_prog_run include/linux/filter.h:600 [inline]
> bpf_prog_run_xdp include/linux/filter.h:775 [inline]
> bpf_prog_run_generic_xdp+0x57e/0x11e0 net/core/dev.c:4721
> netif_receive_generic_xdp net/core/dev.c:4807 [inline]
> do_xdp_generic+0x35c/0x770 net/core/dev.c:4866
> tun_get_user+0x2340/0x3ca0 drivers/net/tun.c:1919
> tun_chr_write_iter+0xe8/0x210 drivers/net/tun.c:2043
> call_write_iter include/linux/fs.h:1871 [inline]
> new_sync_write fs/read_write.c:491 [inline]
> vfs_write+0x650/0xe40 fs/read_write.c:584
> ksys_write+0x12f/0x250 fs/read_write.c:637
> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
> entry_SYSCALL_64_after_hwframe+0x63/0xcd
>
> xdp->frame_sz > PAGE_SIZE check was introduced in commit c8741e2bfe87
> ("xdp: Allow bpf_xdp_adjust_tail() to grow packet size"). But Jesper
> Dangaard Brouer <[email protected]> noted that after introducing the
> xdp_init_buff() which all XDP driver use - it's safe to remove this
> check. The original intend was to catch cases where XDP drivers have
> not been updated to use xdp.frame_sz, but that is not longer a concern
> (since xdp_init_buff).
>
> Running the initial syzkaller repro it was discovered that the
> contiguous physical memory allocation is used for both xdp paths in
> tun_get_user(), e.g. tun_build_skb() and tun_alloc_skb(). It was also
> stated by Jesper Dangaard Brouer <[email protected]> that XDP can
> work on higher order pages, as long as this is contiguous physical
> memory (e.g. a page).
>
> Reported-and-tested-by: [email protected]
> Closes: https://lore.kernel.org/all/[email protected]/T/
> Link: https://syzkaller.appspot.com/bug?extid=f817490f5bd20541b90a
> Link: https://lore.kernel.org/all/[email protected]/T/
> Fixes: 43b5169d8355 ("net, xdp: Introduce xdp_init_buff utility routine")
> Signed-off-by: Andrew Kanner <[email protected]>
> ---
Acked-by: Jesper Dangaard Brouer <[email protected]>
You can include that ACK in V5.
> net/core/filter.c | 6 ------
> 1 file changed, 6 deletions(-)
>
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 06ba0e56e369..28a59596987a 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -4116,12 +4116,6 @@ BPF_CALL_2(bpf_xdp_adjust_tail, struct xdp_buff *, xdp, int, offset)
> if (unlikely(data_end > data_hard_end))
> return -EINVAL;
>
> - /* ALL drivers MUST init xdp->frame_sz, chicken check below */
> - if (unlikely(xdp->frame_sz > PAGE_SIZE)) {
> - WARN_ONCE(1, "Too BIG xdp->frame_sz = %d\n", xdp->frame_sz);
> - return -EINVAL;
> - }
> -
> if (unlikely(data_end < xdp->data + ETH_HLEN))
> return -EINVAL;
>
On Wed, Aug 2, 2023 at 6:09 AM Andrew Kanner <[email protected]> wrote:
>
> Syzkaller reported the following issue:
> =======================================
> Too BIG xdp->frame_sz = 131072
> WARNING: CPU: 0 PID: 5020 at net/core/filter.c:4121
> ____bpf_xdp_adjust_tail net/core/filter.c:4121 [inline]
> WARNING: CPU: 0 PID: 5020 at net/core/filter.c:4121
> bpf_xdp_adjust_tail+0x466/0xa10 net/core/filter.c:4103
> ...
> Call Trace:
> <TASK>
> bpf_prog_4add87e5301a4105+0x1a/0x1c
> __bpf_prog_run include/linux/filter.h:600 [inline]
> bpf_prog_run_xdp include/linux/filter.h:775 [inline]
> bpf_prog_run_generic_xdp+0x57e/0x11e0 net/core/dev.c:4721
> netif_receive_generic_xdp net/core/dev.c:4807 [inline]
> do_xdp_generic+0x35c/0x770 net/core/dev.c:4866
> tun_get_user+0x2340/0x3ca0 drivers/net/tun.c:1919
> tun_chr_write_iter+0xe8/0x210 drivers/net/tun.c:2043
> call_write_iter include/linux/fs.h:1871 [inline]
> new_sync_write fs/read_write.c:491 [inline]
> vfs_write+0x650/0xe40 fs/read_write.c:584
> ksys_write+0x12f/0x250 fs/read_write.c:637
> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
> entry_SYSCALL_64_after_hwframe+0x63/0xcd
>
> xdp->frame_sz > PAGE_SIZE check was introduced in commit c8741e2bfe87
> ("xdp: Allow bpf_xdp_adjust_tail() to grow packet size"). But Jesper
> Dangaard Brouer <[email protected]> noted that after introducing the
> xdp_init_buff() which all XDP driver use - it's safe to remove this
> check. The original intend was to catch cases where XDP drivers have
> not been updated to use xdp.frame_sz, but that is not longer a concern
> (since xdp_init_buff).
>
> Running the initial syzkaller repro it was discovered that the
> contiguous physical memory allocation is used for both xdp paths in
> tun_get_user(), e.g. tun_build_skb() and tun_alloc_skb(). It was also
> stated by Jesper Dangaard Brouer <[email protected]> that XDP can
> work on higher order pages, as long as this is contiguous physical
> memory (e.g. a page).
>
> Reported-and-tested-by: [email protected]
> Closes: https://lore.kernel.org/all/[email protected]/T/
> Link: https://syzkaller.appspot.com/bug?extid=f817490f5bd20541b90a
> Link: https://lore.kernel.org/all/[email protected]/T/
> Fixes: 43b5169d8355 ("net, xdp: Introduce xdp_init_buff utility routine")
> Signed-off-by: Andrew Kanner <[email protected]>
Acked-by: Jason Wang <[email protected]>
Thanks
> ---
> net/core/filter.c | 6 ------
> 1 file changed, 6 deletions(-)
>
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 06ba0e56e369..28a59596987a 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -4116,12 +4116,6 @@ BPF_CALL_2(bpf_xdp_adjust_tail, struct xdp_buff *, xdp, int, offset)
> if (unlikely(data_end > data_hard_end))
> return -EINVAL;
>
> - /* ALL drivers MUST init xdp->frame_sz, chicken check below */
> - if (unlikely(xdp->frame_sz > PAGE_SIZE)) {
> - WARN_ONCE(1, "Too BIG xdp->frame_sz = %d\n", xdp->frame_sz);
> - return -EINVAL;
> - }
> -
> if (unlikely(data_end < xdp->data + ETH_HLEN))
> return -EINVAL;
>
> --
> 2.39.3
>
On Thu, Aug 03, 2023 at 11:20:20AM +0800, Jason Wang wrote:
>
> Acked-by: Jason Wang <[email protected]>
>
> Thanks
>
Thanks, Jason.
I will use this tag in v5, if you don't mind.
PATCH 2/2 will be the same but with more recipients.
--
Andrew Kanner