On Thu, 2019-11-21 at 15:26 +0300, Andrey Ryabinin wrote:
>
> On 11/12/19 9:53 AM, Walter Wu wrote:
>
> > diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> > index 6814d6d6a023..4bfce0af881f 100644
> > --- a/mm/kasan/common.c
> > +++ b/mm/kasan/common.c
> > @@ -102,7 +102,8 @@ EXPORT_SYMBOL(__kasan_check_write);
> > #undef memset
> > void *memset(void *addr, int c, size_t len)
> > {
> > - check_memory_region((unsigned long)addr, len, true, _RET_IP_);
> > + if (!check_memory_region((unsigned long)addr, len, true, _RET_IP_))
> > + return NULL;
> >
> > return __memset(addr, c, len);
> > }
> > @@ -110,8 +111,9 @@ void *memset(void *addr, int c, size_t len)
> > #undef memmove
> > void *memmove(void *dest, const void *src, size_t len)
> > {
> > - check_memory_region((unsigned long)src, len, false, _RET_IP_);
> > - check_memory_region((unsigned long)dest, len, true, _RET_IP_);
> > + if (!check_memory_region((unsigned long)src, len, false, _RET_IP_) ||
> > + !check_memory_region((unsigned long)dest, len, true, _RET_IP_))
> > + return NULL;
> >
> > return __memmove(dest, src, len);
> > }
> > @@ -119,8 +121,9 @@ void *memmove(void *dest, const void *src, size_t len)
> > #undef memcpy
> > void *memcpy(void *dest, const void *src, size_t len)
> > {
> > - check_memory_region((unsigned long)src, len, false, _RET_IP_);
> > - check_memory_region((unsigned long)dest, len, true, _RET_IP_);
> > + if (!check_memory_region((unsigned long)src, len, false, _RET_IP_) ||
> > + !check_memory_region((unsigned long)dest, len, true, _RET_IP_))
> > + return NULL;
> >
>
> I realized that we are going a wrong direction here. Entirely skipping mem*() operation on any
> poisoned shadow value might only make things worse. Some bugs just don't have any serious consequences,
> but skipping the mem*() ops entirely might introduce such consequences, which wouldn't happen otherwise.
>
> So let's keep this code as this, no need to check the result of check_memory_region().
>
>
Ok, we just need to determine whether size is negative number. If yes
then KASAN produce report and continue to execute mem*(). right?
