[PATCH] bthread: disable ASan accounting for fibers on 32-bit sandbox

[Sascha Hauer]

On Fri, Mar 19, 2021 at 09:46:21AM +0100, Ahmad Fatoum wrote:
> For the sandbox architecture, we use __sanitizer_start_switch_fiber
> and __sanitizer_finish_switch_fiber to tell ASan when we switch stacks.
> 
> If we don't, ASan complains that:
> 
>   ==2472828==WARNING: ASan is ignoring requested __asan_handle_no_return:
>     stack top: 0xff9fc000; bottom 0xf3be8000; size: 0x0be14000 (199311360)
>   False positive error reports may follow
>   For details see https://github.com/google/sanitizers/issues/189
> 
> This works on 64-bit sandbox, but 32-bit sandbox currently crashes on
> bthread -v:
> 
> ==2469590==AddressSanitizer CHECK failed: ../../../../../src/libsanitizer/asan/asan_poisoning.cpp:37 "((AddrIsAlignedByGranularity(addr + size))) != (0)" (0x0, 0x0)
>     #0 0xf7a4aa46 in AsanCheckFailed ../../../../../src/libsanitizer/asan/asan_rtl.cpp:73
>     #1 0xf7a6b5cf in __sanitizer::CheckFailed(char const*, int, char const*, unsigned long long, unsigned long long) ../../../../../src/libsanitizer/sanitizer_common/sanitizer_termination.cpp:78
>     #2 0xf7a4489f in __asan::PoisonShadow(unsigned long, unsigned long, unsigned char) ../../../../../src/libsanitizer/asan/asan_poisoning.cpp:37
>     #3 0xf7a4c81b in __asan_handle_no_return ../../../../../src/libsanitizer/asan/asan_rtl.cpp:595
>     #4 0x566a1ce7 in bthread_schedule /home/a3f/dl/barebox-stm32mp/common/bthread.c:178
>     #5 0x566a1d54 in bthread_reschedule /home/a3f/dl/barebox-stm32mp/common/bthread.c:165
>     #6 0x566a1d80 in bthread_trampoline /home/a3f/dl/barebox-stm32mp/common/bthread.c:56
>     #7 0x567f5bfb in coroutine_bootstrap (/home/a3f/dl/build/barebox/sandbox/barebox+0x1bdbfb)
>     #8 0x567f5c4b in coroutine_trampoline (/home/a3f/dl/build/barebox/sandbox/barebox+0x1bdc4b)
>     #9 0xf7f7056f  (linux-gate.so.1+0x56f)
>     #10 0xf7f70558  (linux-gate.so.1+0x558)
>     #11 0x56892fff  (/home/a3f/dl/build/barebox/sandbox/barebox+0x25afff)
> 
> Just disable the special ASan accounting there until this is figured
> out. bthreads still function there, but ASan may yield false positives
> according to the message. This does not affect non-sandbox platforms.
> 
> Signed-off-by: Ahmad Fatoum <ahmad at a3f.at>

Applied, thanks

Sascha

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