[llvm-dev] initialization-order-fiasco in MCTargetDesc/X86MCAsmInfo.cpp

[Kostya Serebryany via llvm-dev]

On Fri, Nov 11, 2016 at 2:29 PM, Mehdi Amini <mehdi.amini at apple.com> wrote:

> It seems that the culprit is llvm/unittests/MC/DwarfLineTables.cpp, which
> has a global variable “Context” that initializes all of LLVM
> (InitializeAllTargetInfos(), InitializeAllTargetMCs(), InitializeAllDisassemblers(),
> etc.).
>
> It seems to have been there forever, but just got uncovered by “luck” (or
> lack of thereof) by ASAN.
>
> Fixed in r286647 hopefully.
>

yep!

thanks!


>
> On Nov 11, 2016, at 1:44 PM, Kostya Serebryany <kcc at google.com> wrote:
>
> Mehdi, Teresa,
>
> Not sure if this is caused by one of your recent commits, or by someone
> else's,
> please excuse me if that's unrelated to your work...
>
> http://lab.llvm.org:8011/builders/sanitizer-x86_64-
> linux-fast/builds/542/steps/check-llvm%20asan/logs/stdio
>
> ==26383==ERROR: AddressSanitizer: initialization-order-fiasco on address 0x000002ef41d8 at pc 0x0000009d1aa5 bp 0x7ffd0cd72b50 sp 0x7ffd0cd72b48
> READ of size 4 at 0x000002ef41d8 thread T0
>     #0 0x9d1aa4 in getValue /mnt/b/sanitizer-buildbot3/sanitizer-x86_64-linux-fast/build/llvm/include/llvm/Support/CommandLine.h:1229:38
>     #1 0x9d1aa4 in operator AsmWriterFlavorTy /mnt/b/sanitizer-buildbot3/sanitizer-x86_64-linux-fast/build/llvm/include/llvm/Support/CommandLine.h:1233
>     #2 0x9d1aa4 in llvm::X86ELFMCAsmInfo::X86ELFMCAsmInfo(llvm::Triple const&) /mnt/b/sanitizer-buildbot3/sanitizer-x86_64-linux-fast/build/llvm/lib/Target/X86/MCTargetDesc/X86MCAsmInfo.cpp:100
>     #3 0x9cf3e1 in createX86MCAsmInfo(llvm::MCRegisterInfo const&, llvm::Triple const&) /mnt/b/sanitizer-buildbot3/sanitizer-x86_64-linux-fast/build/llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp:179:15
>     #4 0x421020 in createMCAsmInfo /mnt/b/sanitizer-buildbot3/sanitizer-x86_64-linux-fast/build/llvm/include/llvm/Support/TargetRegistry.h:298:12
>     #5 0x421020 in Context /mnt/b/sanitizer-buildbot3/sanitizer-x86_64-linux-fast/build/llvm/unittests/MC/DwarfLineTables.cpp:41
>     #6 0x421020 in __cxx_global_var_init /mnt/b/sanitizer-buildbot3/sanitizer-x86_64-linux-fast/build/llvm/unittests/MC/DwarfLineTables.cpp:49
>     #7 0x421020 in _GLOBAL__sub_I_DwarfLineTables.cpp /mnt/b/sanitizer-buildbot3/sanitizer-x86_64-linux-fast/build/llvm/unittests/MC/DwarfLineTables.cpp
>     #8 0x102efcc in __libc_csu_init (/mnt/b/sanitizer-buildbot3/sanitizer-x86_64-linux-fast/build/llvm_build_asan/unittests/MC/MCTests+0x102efcc)
>     #9 0x7f57fa3d8ed4 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21ed4)
>     #10 0x4b4222 in _start (/mnt/b/sanitizer-buildbot3/sanitizer-x86_64-linux-fast/build/llvm_build_asan/unittests/MC/MCTests+0x4b4222)
>
> 0x000002ef41d8 is located 152 bytes inside of global variable 'AsmWriterFlavor' defined in '/mnt/b/sanitizer-buildbot3/sanitizer-x86_64-linux-fast/build/llvm/lib/Target/X86/MCTargetDesc/X86MCAsmInfo.cpp:31:1' (0x2ef4140) of size 600
>   registered at:
>     #0 0x4c63fd in __asan_register_globals.part.15 /mnt/b/sanitizer-buildbot3/sanitizer-x86_64-linux-fast/build/llvm/projects/compiler-rt/lib/asan/asan_globals.cc:338
>     #1 0x9d3f9b in asan.module_ctor (/mnt/b/sanitizer-buildbot3/sanitizer-x86_64-linux-fast/build/llvm_build_asan/unittests/MC/MCTests+0x9d3f9b)
>
>
> The reports seems correct.
> The flag object AsmWriterFlavor is used before it is initialized in
> initialization of some other global object.
>
> This makes the asan bot red... :(
>
> Thanks,
> --kcc
>
>
>
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