Re: [Qemu-devel] [PATCH 12/12] WIP ucontext: annotate coroutine stack for ASAN

["Marc-André Lureau" <marcandre.lureau@redhat.com>]

Hi

----- Original Message -----
> On Fri, Dec 08, 2017 at 01:58:25AM +0100, Marc-André Lureau wrote:
> > Not strictly necessary, but it may help ASAN and remove some false
> > positives.
> > 
> > Sadly, this annotation produces an ASAN error:
> > 
> > $ tests/test-coroutine -p /basic/lifecycle
> > /basic/lifecycle: ==27655==WARNING: ASan doesn't fully support
> > makecontext/swapcontext functions and may produce false positives in some
> > cases!
> > ==27655==AddressSanitizer CHECK failed:
> > /builddir/build/BUILD/compiler-rt-4.0.1.src/lib/asan/asan_poisoning.cc:38
> > "((AddrIsAlignedByGranularity(addr + size))) != (0)" (0x0, 0x0)
> >     #0 0x55d1e4e8a695 in __asan::AsanCheckFailed(char const*, int, char
> >     const*, unsigned long long, unsigned long long)
> >     (/home/elmarco/src/qq/build/tests/test-coroutine+0x1c0695)
> >     #1 0x55d1e4ea6235 in __sanitizer::CheckFailed(char const*, int, char
> >     const*, unsigned long long, unsigned long long)
> >     (/home/elmarco/src/qq/build/tests/test-coroutine+0x1dc235)
> >     #2 0x55d1e4e82ea4 in __asan::PoisonShadow(unsigned long, unsigned long,
> >     unsigned char)
> >     (/home/elmarco/src/qq/build/tests/test-coroutine+0x1b8ea4)
> >     #3 0x55d1e4dde1e7 in __asan::FakeStack::Destroy(int)
> >     (/home/elmarco/src/qq/build/tests/test-coroutine+0x1141e7)
> >     #4 0x55d1e528b775 in qemu_coroutine_switch
> >     /home/elmarco/src/qq/util/coroutine-ucontext.c:219:9
> >     #5 0x55d1e528b18d in coroutine_trampoline
> >     /home/elmarco/src/qq/util/coroutine-ucontext.c:114:9
> >     #6 0x7fb3e0087bef  (/lib64/libc.so.6+0x50bef)
> 
> Looks like a step in the right direction.
> 

Thanks Stefan, I suppose this is not irony ;)

I'll try to nail down the issue and make a small reproducer for ASAN.