From: Eric Dumazet <[email protected]>
syzbot reported access to unitialized memory in mbind() [1]
Issue came with commit bda420b98505 ("numa balancing: migrate on
fault among multiple bound nodes")
This commit added a new bit in MPOL_MODE_FLAGS, but only checked
valid combination (MPOL_F_NUMA_BALANCING can only be used with MPOL_BIND)
in do_set_mempolicy()
This patch moves the check in sanitize_mpol_flags() so that it
is also used by mbind()
[1]
BUG: KMSAN: uninit-value in __mpol_equal+0x567/0x590 mm/mempolicy.c:2260
__mpol_equal+0x567/0x590 mm/mempolicy.c:2260
mpol_equal include/linux/mempolicy.h:105 [inline]
vma_merge+0x4a1/0x1e60 mm/mmap.c:1190
mbind_range+0xcc8/0x1e80 mm/mempolicy.c:811
do_mbind+0xf42/0x15f0 mm/mempolicy.c:1333
kernel_mbind mm/mempolicy.c:1483 [inline]
__do_sys_mbind mm/mempolicy.c:1490 [inline]
__se_sys_mbind+0x437/0xb80 mm/mempolicy.c:1486
__x64_sys_mbind+0x19d/0x200 mm/mempolicy.c:1486
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x44/0xae
Uninit was created at:
slab_alloc_node mm/slub.c:3221 [inline]
slab_alloc mm/slub.c:3230 [inline]
kmem_cache_alloc+0x751/0xff0 mm/slub.c:3235
mpol_new mm/mempolicy.c:293 [inline]
do_mbind+0x912/0x15f0 mm/mempolicy.c:1289
kernel_mbind mm/mempolicy.c:1483 [inline]
__do_sys_mbind mm/mempolicy.c:1490 [inline]
__se_sys_mbind+0x437/0xb80 mm/mempolicy.c:1486
__x64_sys_mbind+0x19d/0x200 mm/mempolicy.c:1486
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x44/0xae
=====================================================
Kernel panic - not syncing: panic_on_kmsan set ...
CPU: 0 PID: 15049 Comm: syz-executor.0 Tainted: G B 5.15.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1ff/0x28e lib/dump_stack.c:106
dump_stack+0x25/0x28 lib/dump_stack.c:113
panic+0x44f/0xdeb kernel/panic.c:232
kmsan_report+0x2ee/0x300 mm/kmsan/report.c:186
__msan_warning+0xd7/0x150 mm/kmsan/instrumentation.c:208
__mpol_equal+0x567/0x590 mm/mempolicy.c:2260
mpol_equal include/linux/mempolicy.h:105 [inline]
vma_merge+0x4a1/0x1e60 mm/mmap.c:1190
mbind_range+0xcc8/0x1e80 mm/mempolicy.c:811
do_mbind+0xf42/0x15f0 mm/mempolicy.c:1333
kernel_mbind mm/mempolicy.c:1483 [inline]
__do_sys_mbind mm/mempolicy.c:1490 [inline]
__se_sys_mbind+0x437/0xb80 mm/mempolicy.c:1486
__x64_sys_mbind+0x19d/0x200 mm/mempolicy.c:1486
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f4a41b2c709
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4a3f0a3188 EFLAGS: 00000246 ORIG_RAX: 00000000000000ed
RAX: ffffffffffffffda RBX: 00007f4a41c30f60 RCX: 00007f4a41b2c709
RDX: 0000000000002001 RSI: 0000000000c00007 RDI: 0000000020012000
RBP: 00007f4a41b86cb4 R08: 0000000000000000 R09: 0000010000000002
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4a42164b2f R14: 00007f4a3f0a3300 R15: 0000000000022000
Fixes: bda420b98505 ("numa balancing: migrate on fault among multiple bound nodes")
Signed-off-by: Eric Dumazet <[email protected]>
Reported-by: syzbot <[email protected]>
Cc: "Huang, Ying" <[email protected]>
Cc: Mel Gorman <[email protected]>
---
v2: fix compiler warning reported by kernel test robot <[email protected]>
mm/mempolicy.c | 16 +++++-----------
1 file changed, 5 insertions(+), 11 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 1592b081c58ef6dd63c6f075ad24722f2be7cb5d..d12e0608fced235dc9137d0628437046299c7cfc 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -856,16 +856,6 @@ static long do_set_mempolicy(unsigned short mode, unsigned short flags,
goto out;
}
- if (flags & MPOL_F_NUMA_BALANCING) {
- if (new && new->mode == MPOL_BIND) {
- new->flags |= (MPOL_F_MOF | MPOL_F_MORON);
- } else {
- ret = -EINVAL;
- mpol_put(new);
- goto out;
- }
- }
-
ret = mpol_set_nodemask(new, nodes, scratch);
if (ret) {
mpol_put(new);
@@ -1458,7 +1448,11 @@ static inline int sanitize_mpol_flags(int *mode, unsigned short *flags)
return -EINVAL;
if ((*flags & MPOL_F_STATIC_NODES) && (*flags & MPOL_F_RELATIVE_NODES))
return -EINVAL;
-
+ if (*flags & MPOL_F_NUMA_BALANCING) {
+ if (*mode != MPOL_BIND)
+ return -EINVAL;
+ *flags |= (MPOL_F_MOF | MPOL_F_MORON);
+ }
return 0;
}
--
2.33.0.800.g4c38ced690-goog
Hi, Eric,
Eric Dumazet <[email protected]> writes:
> From: Eric Dumazet <[email protected]>
>
> syzbot reported access to unitialized memory in mbind() [1]
>
> Issue came with commit bda420b98505 ("numa balancing: migrate on
> fault among multiple bound nodes")
>
> This commit added a new bit in MPOL_MODE_FLAGS, but only checked
> valid combination (MPOL_F_NUMA_BALANCING can only be used with MPOL_BIND)
> in do_set_mempolicy()
>
> This patch moves the check in sanitize_mpol_flags() so that it
> is also used by mbind()
Good catch! Thanks! When MPOL_F_NUMA_BALANCING is introduced, it is
intended to be used with set_memopolicy() syscall only, it is not
allowed to be used with mbind() syscall at least for now. But I
misunderstood the original code apparently.
So I think it may be better to return EINVAL for mbind() +
MPOL_F_NUMA_BALANCING?
Best Regards,
Huang, Ying