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author | Qian Cai <cai@lca.pw> | 2020-07-17 16:01:01 +1000 |
---|---|---|
committer | Stephen Rothwell <sfr@canb.auug.org.au> | 2020-07-17 20:31:21 +1000 |
commit | db42bf61f88160677e3689943d9b49f067312de5 (patch) | |
tree | c5d297ad0d05479b9814c811fdb45583e976e824 | |
parent | db7b8002f00e46eec8f758df55aafdd07402e4d4 (diff) | |
download | linux-db42bf61f88160677e3689943d9b49f067312de5.tar.gz linux-db42bf61f88160677e3689943d9b49f067312de5.tar.xz |
mm/kmemleak: silence KCSAN splats in checksum
Even if KCSAN is disabled for kmemleak, update_checksum() could still call
crc32() (which is outside of kmemleak.c) to dereference object->pointer.
Thus, the value of object->pointer could be accessed concurrently as
noticed by KCSAN,
BUG: KCSAN: data-race in crc32_le_base / do_raw_spin_lock
write to 0xffffb0ea683a7d50 of 4 bytes by task 23575 on cpu 12:
do_raw_spin_lock+0x114/0x200
debug_spin_lock_after at kernel/locking/spinlock_debug.c:91
(inlined by) do_raw_spin_lock at kernel/locking/spinlock_debug.c:115
_raw_spin_lock+0x40/0x50
__handle_mm_fault+0xa9e/0xd00
handle_mm_fault+0xfc/0x2f0
do_page_fault+0x263/0x6f9
page_fault+0x34/0x40
read to 0xffffb0ea683a7d50 of 4 bytes by task 839 on cpu 60:
crc32_le_base+0x67/0x350
crc32_le_base+0x67/0x350:
crc32_body at lib/crc32.c:106
(inlined by) crc32_le_generic at lib/crc32.c:179
(inlined by) crc32_le at lib/crc32.c:197
kmemleak_scan+0x528/0xd90
update_checksum at mm/kmemleak.c:1172
(inlined by) kmemleak_scan at mm/kmemleak.c:1497
kmemleak_scan_thread+0xcc/0xfa
kthread+0x1e0/0x200
ret_from_fork+0x27/0x50
If a shattered value was returned due to a data race, it will be corrected
in the next scan. Thus, let KCSAN ignore all reads in the region to
silence KCSAN in case the write side is non-atomic.
Link: http://lkml.kernel.org/r/20200317182754.2180-1-cai@lca.pw
Signed-off-by: Qian Cai <cai@lca.pw>
Suggested-by: Marco Elver <elver@google.com>
Acked-by: Marco Elver <elver@google.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
-rw-r--r-- | mm/kmemleak.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/mm/kmemleak.c b/mm/kmemleak.c index 29a684a4656a..4e644dc074b1 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -1169,8 +1169,10 @@ static bool update_checksum(struct kmemleak_object *object) u32 old_csum = object->checksum; kasan_disable_current(); + kcsan_disable_current(); object->checksum = crc32(0, (void *)object->pointer, object->size); kasan_enable_current(); + kcsan_enable_current(); return object->checksum != old_csum; } |