Bug#842642: clang-3.9: memory sanitizer segfaults immediately

[Sylvestre Ledru]

I could apply upstream-msan-prevent-initialization-failure.diff  to 3.8 
but not the two others, could you share yours?
Thanks
S

Le 11/11/2016 à 09:52, Norbert Lange a écrit :
> The same 2 patches also apply to toolchain 3.8.1-15 (with some
> offsets), but I haven`t testing building it
>
> 2016-11-11 1:25 GMT+01:00 Norbert Lange <nolange79 at gmail.com>:
>> BTW. make check-sanitizer would have likely found this issue, might
>> want to enable it?
>> I believe it knows which sanitizers should work
>>
>> 2016-11-11 0:46 GMT+01:00 Norbert Lange <nolange79 at gmail.com>:
>>> Tags: patch
>>>
>>>
>>> Hi,
>>>
>>> I got it working, seems that from the 3 related patched, one is already applied.
>>> The attached archive is the 3 patches and a edited "series" file,
>>> it should be painless for you to integrate it into the debian/patches
>>> directory for 3.9
>>>
>>> I did not try with 3.8 yet (possibly more difficult), building llvm
>>> takes quite a while.
>>>
>>> Kind Regards,
>>> Norbert
>>>
>>> 2016-11-09 11:04 GMT+01:00 Norbert Lange <nolange79 at gmail.com>:
>>>> Hi,
>>>>
>>>> researched a bit further and the same compiled programm will run fine
>>>> on debian jessie.
>>>> I tracked it down to being caused by a newer glibc version [1][2],
>>>> apparently during loading of shared libs, glibc can now allocate
>>>> memory which messes up sanitzers (mostly in more subtile ways than the
>>>> memory sanitizer).
>>>>
>>>> The result is, that if stretch will ship with the current glibc, clang
>>>> and gcc (I dont think its patched there either), then the sanitizers
>>>> won`t be usable.
>>>> 1) revert the fix in glibc. Would have the advantage that "sanitized"
>>>> binaries compiled from current and older clang/gcc versions will work
>>>> 2) adopt the fixed from upstream [3][4] (possibly more) into clang
>>>> (and possibly gcc).
>>>> or maybe both?
>>>>
>>>> Kind Regards,
>>>> Norbert
>>>>
>>>> PS. shouldn`t the testsuite catch these bugs?
>>>>
>>>> [1] https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=24e2b1cede1952d7d4411a3cafd25dd8593dab9f
>>>> [2] https://llvm.org/bugs/show_bug.cgi?id=27310
>>>> [3] https://github.com/llvm-mirror/compiler-rt/commit/827ea206c1078fc7c7da287984a7ba4563390589
>>>> [4] https://github.com/llvm-mirror/compiler-rt/commit/570ee9dd7a6f90b0370a86535cbde6738d0ccf67
>>>>
>>>> 2016-10-31 21:43 GMT+01:00 Norbert Lange <nolange79 at gmail.com>:
>>>>> On Mon, 31 Oct 2016 08:38:21 +0100 Sylvestre Ledru <sylvestre at debian.org> wrote:
>>>>>> Le 31/10/2016 à 00:39, Norbert Lange a écrit :
>>>>>>> Package: clang-3.9
>>>>>>> Version: 1:3.9-2
>>>>>>> Severity: normal
>>>>>>>
>>>>>>> Dear Maintainer,
>>>>>>>
>>>>>>> The memory sanitizer is unusable as it segfaults during initialization.
>>>>>>> To reproduce:
>>>>>>> echo 'int main() { return 0; }' >/tmp/test.c
>>>>>>> clang -fsanitize=memory -o test test.c
>>>>>> can you try with clang-3.9 instead?
>>>>> Same thing, output:
>>>>>
>>>>> $ clang-3.9 -fsanitize=memory -o test test.c -v
>>>>> clang version 3.9.0-2 (tags/RELEASE_390/final)
>>>>> Target: x86_64-pc-linux-gnu
>>>>> Thread model: posix
>>>>> InstalledDir: /usr/bin
>>>>> Found candidate GCC installation: /usr/bin/../lib/gcc/i686-linux-gnu/6
>>>>> Found candidate GCC installation: /usr/bin/../lib/gcc/i686-linux-gnu/6.2.0
>>>>> Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/5
>>>>> Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/5.4.1
>>>>> Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/6
>>>>> Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/6.2.0
>>>>> Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/6
>>>>> Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/6.2.0
>>>>> Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5
>>>>> Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.4.1
>>>>> Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
>>>>> Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.2.0
>>>>> Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/6.2.0
>>>>> Candidate multilib: .;@m64
>>>>> Candidate multilib: 32;@m32
>>>>> Candidate multilib: x32;@mx32
>>>>> Selected multilib: .;@m64
>>>>>   "/usr/lib/llvm-3.9/bin/clang" -cc1 -triple x86_64-pc-linux-gnu
>>>>> -emit-obj -mrelax-all -disable-free -disable-llvm-verifier
>>>>> -discard-value-names -main-file-name test.c -mrelocation-model static
>>>>> -mthread-model posix -mdisable-fp-elim -fmath-errno -masm-verbose
>>>>> -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu
>>>>> x86-64 -v -dwarf-column-info -debugger-tuning=gdb -resource-dir
>>>>> /usr/lib/llvm-3.9/bin/../lib/clang/3.9.0 -internal-isystem
>>>>> /usr/local/include -internal-isystem
>>>>> /usr/lib/llvm-3.9/bin/../lib/clang/3.9.0/include
>>>>> -internal-externc-isystem /usr/include/x86_64-linux-gnu
>>>>> -internal-externc-isystem /include -internal-externc-isystem
>>>>> /usr/include -fdebug-compilation-dir /tmp -ferror-limit 19
>>>>> -fmessage-length 135 -fsanitize=memory
>>>>> -fsanitize-blacklist=/usr/lib/llvm-3.9/bin/../lib/clang/3.9.0/msan_blacklist.txt
>>>>> -fno-assume-sane-operator-new -fobjc-runtime=gcc
>>>>> -fdiagnostics-show-option -fcolor-diagnostics -o /tmp/test-2d4d2c.o -x
>>>>> c test.c
>>>>> clang -cc1 version 3.9.0 based upon LLVM 3.9.0 default target
>>>>> x86_64-pc-linux-gnu
>>>>> ignoring nonexistent directory "/include"
>>>>> #include "..." search starts here:
>>>>> #include <...> search starts here:
>>>>>   /usr/local/include
>>>>>   /usr/lib/llvm-3.9/bin/../lib/clang/3.9.0/include
>>>>>   /usr/include/x86_64-linux-gnu
>>>>>   /usr/include
>>>>> End of search list.
>>>>>   "/usr/bin/ld" --hash-style=both --eh-frame-hdr -m elf_x86_64
>>>>> -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o test
>>>>> /usr/bin/../lib/gcc/x86_64-linux-gnu/6.2.0/../../../x86_64-linux-gnu/crt1.o
>>>>> /usr/bin/../lib/gcc/x86_64-linux-gnu/6.2.0/../../../x86_64-linux-gnu/crti.o
>>>>> /usr/bin/../lib/gcc/x86_64-linux-gnu/6.2.0/crtbegin.o
>>>>> -L/usr/bin/../lib/gcc/x86_64-linux-gnu/6.2.0
>>>>> -L/usr/bin/../lib/gcc/x86_64-linux-gnu/6.2.0/../../../x86_64-linux-gnu
>>>>> -L/lib/x86_64-linux-gnu -L/lib/../lib64 -L/usr/lib/x86_64-linux-gnu
>>>>> -L/usr/bin/../lib/gcc/x86_64-linux-gnu/6.2.0/../../..
>>>>> -L/usr/lib/llvm-3.9/bin/../lib -L/lib -L/usr/lib -whole-archive
>>>>> /usr/lib/llvm-3.9/bin/../lib/clang/3.9.0/lib/linux/libclang_rt.msan-x86_64.a
>>>>> -no-whole-archive
>>>>> --dynamic-list=/usr/lib/llvm-3.9/bin/../lib/clang/3.9.0/lib/linux/libclang_rt.msan-x86_64.a.syms
>>>>> /tmp/test-2d4d2c.o --no-as-needed -lpthread -lrt -lm -ldl -lgcc
>>>>> --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s
>>>>> --no-as-needed /usr/bin/../lib/gcc/x86_64-linux-gnu/6.2.0/crtend.o
>>>>> /usr/bin/../lib/gcc/x86_64-linux-gnu/6.2.0/../../../x86_64-linux-gnu/crtn.o