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

[Norbert Lange]

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