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Re: libsanitizer merge from upstream r191666
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Konstantin Serebryany <konstantin dot s dot serebryany at gmail dot com>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>, Dodji Seketeli <dodji at redhat dot com>, Dmitry Vyukov <dvyukov at google dot com>
- Date: Fri, 15 Nov 2013 15:33:48 +0100
- Subject: Re: libsanitizer merge from upstream r191666
- Authentication-results: sourceware.org; auth=none
- References: <CAGQ9bdw+VW=yF+vaqE_0GkyHUChL_vp3cABZf-FuNYoHo3g=eg at mail dot gmail dot com> <20131029135236 dot GB30970 at tucnak dot zalov dot cz> <CAGQ9bdwHhvDksRcWqn3udeDy=7xAtXueo63Km_h=To9PZ7Li8g at mail dot gmail dot com> <20131114153349 dot GC27813 at tucnak dot zalov dot cz> <CAGQ9bdwc8gw1Am1T9-jKdweiGkThKy-n7m65CMLSHsJnAp7DHA at mail dot gmail dot com> <20131114180817 dot GF27813 at tucnak dot zalov dot cz> <20131114180906 dot GE21875 at tucnak dot zalov dot cz> <CAGQ9bdz++2cDOATnJ0B632J1bS-mMv03XPPnukU0W+cSgGbTTQ at mail dot gmail dot com> <20131115101018 dot GB892 at tucnak dot redhat dot com> <CAGQ9bdyZcjPkt89cf-bEGjCP54Wdhobzk7Wa4G+ETYMsvdctwg at mail dot gmail dot com>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Fri, Nov 15, 2013 at 06:12:07PM +0400, Konstantin Serebryany wrote:
> I afraid it actually wants the header (magic, descr, pc) to be in the
> first 3 words in the
> memory returned by __asan_stack_malloc_*
> FakeStack::AddrIsInFakeStack(addr) returns the beginning of the allocated chunk
> and then AsanThread::GetFrameNameByAddr expects the header to be there.
Can it be changed? I mean, adding potentially very large first red zone
would be quite expensive, and would have to be done unconditionally, even
when not using fake stacks.
I mean, in AsanThread::GetFrameNameByAddr do (pseudo patch):
+ u8 *shadow_bottom;
if (AddrIsInStack(addr)) {
bottom = stack_bottom();
+ shadow_bottom = (u8*)MemToShadow(bottom);
} else if (has_fake_stack()) {
bottom = fake_stack()->AddrIsInFakeStack(addr);
CHECK(bottom);
- *offset = addr - bottom;
- *frame_pc = ((uptr*)bottom)[2];
- return (const char *)((uptr*)bottom)[1];
+ shadow_bottom = (u8*)MemToShadow(bottom);
+ if (*shadow_bottom == kAsanStackLeftRedzoneMagic) {
+ *offset = addr - bottom;
+ *frame_pc = ((uptr*)bottom)[2];
+ return (const char *)((uptr*)bottom)[1];
+ }
}
uptr aligned_addr = addr & ~(SANITIZER_WORDSIZE/8 - 1); // align addr.
u8 *shadow_ptr = (u8*)MemToShadow(aligned_addr);
- u8 *shadow_bottom = (u8*)MemToShadow(bottom);
Jakub