2015-09-08 4:42 GMT+03:00 Xishi Qiu <qiuxishi@xxxxxxxxxx>:
> The shadow which correspond 16 bytes may span 2 or 3 bytes. If shadow
> only take 2 bytes, we can return in "if (likely(!last_byte)) ...", but
> it calculates wrong, so fix it.
>
Please, be more specific. Describe what is wrong with the current code and why,
what's the effect of this bug and how you fixed it.
> Signed-off-by: Xishi Qiu <qiuxishi@xxxxxxxxxx>
> ---
> 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 7b28e9c..8da2114 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);
> --
> 1.7.1
>
>
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