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| author | Xishi Qiu <qiuxishi@huawei.com> | 2015-09-17 16:01:43 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-09-17 21:16:07 -0700 |
| commit | 8d77a6d18ae9ccfd5eee1cc551ee4ac27fd41464 (patch) | |
| tree | 98b1b0a49f06a7ee0fec465fd9175de23ecc58a1 /mm/kasan | |
| parent | 3aaf14da807a4e9931a37f21e4251abb8a67021b (diff) | |
| download | lwn-8d77a6d18ae9ccfd5eee1cc551ee4ac27fd41464.tar.gz lwn-8d77a6d18ae9ccfd5eee1cc551ee4ac27fd41464.zip | |
kasan: fix last shadow judgement in memory_is_poisoned_16()
The shadow which correspond 16 bytes memory may span 2 or 3 bytes. If
the memory is aligned on 8, then the shadow takes only 2 bytes. So we
check "shadow_first_bytes" is enough, and need not to call
"memory_is_poisoned_1(addr + 15);". But the code "if
(likely(!last_byte))" is wrong judgement.
e.g. addr=0, so last_byte = 15 & KASAN_SHADOW_MASK = 7, then the code
will continue to call "memory_is_poisoned_1(addr + 15);"
Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Michal Marek <mmarek@suse.cz>
Cc: <zhongjiang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/kasan')
| -rw-r--r-- | mm/kasan/kasan.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c index 7b28e9cdf1c7..8da211411b57 100644 --- a/mm/kasan/kasan.c +++ b/mm/kasan/kasan.c @@ -135,12 +135,11 @@ static __always_inline bool memory_is_poisoned_16(unsigned long addr) if (unlikely(*shadow_addr)) { u16 shadow_first_bytes = *(u16 *)shadow_addr; - s8 last_byte = (addr + 15) & KASAN_SHADOW_MASK; if (unlikely(shadow_first_bytes)) return true; - if (likely(!last_byte)) + if (likely(IS_ALIGNED(addr, 8))) return false; return memory_is_poisoned_1(addr + 15); |