[compiler-rt] r212815 - [ASan/Win] Don't apply dllexport to __asan_init in the DLL thunk

Fri Jul 11 11:41:22 PDT 2014

Do we require link.exe to be on PATH?  Can you just call it directly?

You can arrange for LIB to contain the path to the asan rt, and then you
should be able to mention it on the link line without much trouble.

On Fri, Jul 11, 2014 at 8:29 AM, Timur Iskhodzhanov <timurrrr at google.com>
wrote:

> Reid, Hans,
>
> I have a hard time writing a simple LIT test that would fail before the
> fix.
>
> Here's a small standalone repro:
> ---- f.cc ----
> #if CONFIG==1
> extern "C" __declspec(dllexport) int f1() {
>   int x = 0;
>   return 1;
> }
> #else
> extern "C" __declspec(dllexport) int f2() {
>   int x = 0;
>   return 2;
> }
> #endif
> --------------
>
> I can repro the failure @r212814 invoking link.exe directly (similar
> to what Chromium does):
> $ clang-cl -fsanitize=address -DCONFIG=1 f.cc -c -Fo1.obj && clang-cl
> -fsanitize=address -DCONFIG=2 f.cc -c -Fo2.obj
> $ link /DLL 1.obj
> %LLVM_BUILD%\lib\clang\3.5.0\lib\windows\clang_rt.asan_dll_thunk-i386.lib
> && \
>    link /DLL 2.obj 1.lib
> %LLVM_BUILD%\lib\clang\3.5.0\lib\windows\clang_rt.asan_dll_thunk-i386.lib
> ...
> clang_rt.asan_dll_thunk-i386.lib(asan_dll_thunk.cc.obj) : error
> LNK2005: ___asan_init_v4 already defined in 1.lib(1.dll)
>
> OK, cool, now I want to get the same error without invoking link.exe
> directly and without knowing the path to the RTL:
> [using the 1.lib generated by the previous link.exe command]
> $ clang-cl -fsanitize=address -LD -DCONFIG=2 f.cc 1.lib -Fe2.dll && echo
> OOPS
>    Creating library 2.lib and object 2.exp
> OOPS
>
> ?!?!
>
> Adding -### reveals that clang-cl calls link.exe with the following
> args at the end of the command line:
> ... "...\clang_rt.asan_dll_thunk-i386.lib" "blablabla.obj" "1.lib"
> and link.exe seems to be sensitive to the order in which the RTL and
> 1.lib appear on the command line!   8)
> $ link /nologo /DLL 2.obj
> %LLVM_BUILD%\lib\clang\3.5.0\lib\windows\clang_rt.asan_dll_thunk-i386.lib
> 1.lib && echo OOPS
> OOPS
> $ link /nologo /DLL 2.obj 1.lib
> %LLVM_BUILD%\lib\clang\3.5.0\lib\windows\clang_rt.asan_dll_thunk-i386.lib
> clang_rt.asan_dll_thunk-i386.lib(asan_dll_thunk.cc.obj) : error
> LNK2005: ___asan_init_v4 already defined in 1.lib(1.dll)
>
> I was unable to pass the lib and the RTL in the order required to
> repro the bug using clang-cl, as clang-cl overrides the order of stuff
> I pass via "-link".
> Any ideas?
> Or maybe it's Chromium/GYP that's doing something wrong?
>
> --
> Tim
>
> 2014-07-11 17:46 GMT+04:00 Timur Iskhodzhanov <timurrrr at google.com>:
> > Author: timurrrr
> > Date: Fri Jul 11 08:46:05 2014
> > New Revision: 212815
> >
> > URL: http://llvm.org/viewvc/llvm-project?rev=212815&view=rev
> > Log:
> > [ASan/Win] Don't apply dllexport to __asan_init in the DLL thunk
> >
> > This fixes '___asan_init_v4 already defined' errors when linking some of
> Chromium DLLs.
> > Looks like one of the DLL is using a .lib produced while linking another
> DLL and it exploded after r212699.
> > I'm trying to come up with a small testcase...
> >
> > Modified:
> >     compiler-rt/trunk/lib/asan/CMakeLists.txt
> >     compiler-rt/trunk/lib/sanitizer_common/sanitizer_internal_defs.h
> >
> > Modified: compiler-rt/trunk/lib/asan/CMakeLists.txt
> > URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/CMakeLists.txt?rev=212815&r1=212814&r2=212815&view=diff
> >
> ==============================================================================
> > --- compiler-rt/trunk/lib/asan/CMakeLists.txt (original)
> > +++ compiler-rt/trunk/lib/asan/CMakeLists.txt Fri Jul 11 08:46:05 2014
> > @@ -179,7 +179,7 @@ else()
> >        add_compiler_rt_runtime(clang_rt.asan_dll_thunk-${arch} ${arch}
> STATIC
> >          SOURCES asan_dll_thunk.cc
> >                  $<TARGET_OBJECTS:RTInterception.${arch}>
> > -        CFLAGS ${ASAN_CFLAGS} -DASAN_DLL_THUNK
> > +        CFLAGS ${ASAN_CFLAGS} -DASAN_DLL_THUNK -DSANITIZER_DLL_THUNK
> >          DEFS ${ASAN_COMMON_DEFINITIONS})
> >        add_dependencies(asan clang_rt.asan_dll_thunk-${arch})
> >      endif()
> >
> > Modified:
> compiler-rt/trunk/lib/sanitizer_common/sanitizer_internal_defs.h
> > URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_internal_defs.h?rev=212815&r1=212814&r2=212815&view=diff
> >
> ==============================================================================
> > --- compiler-rt/trunk/lib/sanitizer_common/sanitizer_internal_defs.h
> (original)
> > +++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_internal_defs.h Fri
> Jul 11 08:46:05 2014
> > @@ -17,7 +17,11 @@
> >
> >  // Only use SANITIZER_*ATTRIBUTE* before the function return type!
> >  #if SANITIZER_WINDOWS
> > -# define SANITIZER_INTERFACE_ATTRIBUTE __declspec(dllexport)
> > +# if defined(SANITIZER_DLL_THUNK)
> > +#  define SANITIZER_INTERFACE_ATTRIBUTE
> > +# else
> > +#  define SANITIZER_INTERFACE_ATTRIBUTE __declspec(dllexport)
> > +# endif
> >  // FIXME find out what we need on Windows, if anything.
> >  # define SANITIZER_WEAK_ATTRIBUTE
> >  #elif defined(SANITIZER_GO)
> >
> >
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>
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