[LLVMdev] radr://12777299, "potential pthread/eh bug exposed by libsanitizer"

[Kostya Serebryany]

+glider
The compiler hardly matters here, I would expect the same failures with
clang.
Alex, could you please take a look?

--kcc

On Thu, Nov 29, 2012 at 9:55 PM, Jack Howarth <howarth at bromo.med.uc.edu>wrote:

> Nick,
>    Can you take a quick look at the asan_eh_bug.tar.bz testcase
> I uploaded into the newly opened radr://12777299, "potential
> pthread/eh bug exposed by libsanitizer". The FSF gcc developers
> have ported llvm.org's asan code into FSF gcc (and are keeping
> it synced to the upstream llvm.org code). I have been helping
> with the darwin build and testing -fsanitize=address against the
> complete FSF gcc testsuite. This seems to have exposed a potential
> bug in pthread or eh on darwin under libasan. Hundreds of test cases
> in the g++ and libstdc++ testsuites fail under -fsanitize=address
> in the following manner...
>
> ASAN:SIGSEGV
> =================================================================
> ==2738== ERROR: AddressSanitizer: SEGV on unknown address 0x0000ffd27000
> (pc 0x0000ffd27000 sp 0x7fff55e40828 bp 0x7fff55e408f0 T0)
> AddressSanitizer can not provide additional info.
>     #0 0xffd26fff (/Users/howarth/asan_eh_bug/./cond1_asan.exe+0xf5f67fff)
>     #1 0x7fff8bd827e0 (/usr/lib/system/libdyld.dylib+0x27e0)
>     #2 0x0
> Stats: 0M malloced (0M for red zones) by 3 calls
> Stats: 0M realloced by 0 calls
> Stats: 0M freed by 0 calls
> Stats: 0M really freed by 0 calls
> Stats: 1M (384 full pages) mmaped in 3 calls
>   mmaps   by size class: 7:4095; 8:2047; 9:1023;
>   mallocs by size class: 7:1; 8:1; 9:1;
>   frees   by size class:
>   rfrees  by size class:
> Stats: malloc large: 0 small slow: 3
> ==2738== ABORTING
>
> The failure of...
>
> FAIL: g++.dg/eh/cond1.C -std=c++98 execution test
>
> was used as the test case for the radar report and compiled with...
>
> g++-fsf-4.8 -static-libasan -fsanitize=address -std=c++98 cond1.C -g -O0
> -o cond1_asan.exe
>
> to produce the above failure. When compiled without libasan as...
>
> g++-fsf-4.8 -std=c++98 cond1.C -g -O0 -o cond1_no_asan.exe
>
> the resulting executable runs fine. Debugging this in gdb seems to show
> that the failure
> is occuring in the final call to dyld_stub_pthread_once (). The same test
> case
> compiles fine with -fsanitize=address under llvm 3.2 clang++ and produces
> no runtime errors
> but the code execution path is very different in that case (because of the
> different
> libstdc++).
>     Can you take a quick peek at this and determine if this is a darwin
> pthread or unwinder
> bug or an issue with libasan that FSF gcc's compiler is exposing? Thanks
> in advance for
> any help on this.
>          Jack
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