[cfe-dev] Debug info broken for ASan-instrumented binaries

[Alexey Samsonov]

Hi Martin,

Sorry for the late response.
This is tracked in
https://code.google.com/p/address-sanitizer/issues/detail?id=235
In short - there is a bug in LLVM DWARF generation, that fires rarely on a
regular C++ code (especially with -O0),
but breaks debug info if we instrument the code with ASan. I've looked at
this issue and had some ideas
about how this should be fixed, but didn't finish the work yet.

On Thu, Mar 27, 2014 at 3:04 PM, Kostya Serebryany <kcc at google.com> wrote:

> +samsonov@
>
>
> On Thu, Mar 27, 2014 at 2:46 PM, Richtarsky, Martin <
> martin.richtarsky at sap.com> wrote:
>
>> Hi,
>>
>> I noticed that debugging of AddressSanitizer-instrumented debug binaries
>> is basically impossible since all the symbols are optimized out. It looks
>> like
>> there is something wrong with debug info. I'm getting the same behavior
>> on 3.4 and trunk. Interestingly it works for -fsanitize=undefined. Is
>> this a known
>> issue? There are several related bugs but they are fixed already, e.g.
>> http://llvm.org/bugs/show_bug.cgi?id=11818
>>
>> # cat UnitAsanStackOOB.cpp
>> int main()
>> {
>>     const int len = 10;
>>     char buffer[len];
>>     char *p = &buffer[0];
>>     p[len] = 1;
>>     return 0;
>> }
>>
>> # clang++ -g -o oob_trunk_add -fsanitize=address UnitAsanStackOOB.cpp
>> # gdb oob_trunk_add
>> GNU gdb (GDB) 7.5.1
>> Reading symbols from
>> /local/build/git5/sys/src/clang/AddressSanitizer/test/oob_trunk_add...done.
>> (gdb) b main
>> Breakpoint 1 at 0x495a4a: file UnitAsanStackOOB.cpp, line 3.
>> (gdb) run
>> Starting program:
>> /local/build/git5/sys/src/clang/AddressSanitizer/test/oob_trunk_add
>> [Thread debugging using libthread_db enabled]
>> Using host libthread_db library "/lib64/libthread_db.so.1".
>> Breakpoint 1, main () at UnitAsanStackOOB.cpp:3
>> 3           const int len = 10;
>> (gdb) n
>> 5           char *p = &buffer[0];
>> (gdb) n
>> 6           p[len] = 1;
>> (gdb) p p
>> $1 = <optimized out>
>> (gdb) p len
>> $2 = <optimized out>
>>
>> # clang++ -g -o oob_trunk_und -fsanitize=undefined UnitAsanStackOOB.cpp
>> # gdb oob_trunk_und
>> GNU gdb (GDB) 7.5.1
>>  (gdb) b main
>> Breakpoint 1 at 0x426280: file UnitAsanStackOOB.cpp, line 2.
>> (gdb) run
>> Starting program:
>> /local/build/git5/sys/src/clang/AddressSanitizer/test/oob_trunk_und
>> [Thread debugging using libthread_db enabled]
>> Using host libthread_db library "/lib64/libthread_db.so.1".
>> Breakpoint 1, main () at UnitAsanStackOOB.cpp:2
>> 2       {
>> (gdb) n
>> 3           const int len = 10;
>> (gdb) n
>> 5           char *p = &buffer[0];
>> (gdb) n
>> 6           p[len] = 1;
>> (gdb) p p
>> $1 = 0x7fffffff975e ""
>> (gdb) p len
>> $2 = 10
>>
>> # clang++ -v
>> clang version 3.5.0 (trunk 204863)
>> Target: x86_64-unknown-linux-gnu
>> Thread model: posix
>> Found candidate GCC installation: /usr/lib64/gcc/x86_64-suse-linux/4.3
>> Selected GCC installation: /usr/lib64/gcc/x86_64-suse-linux/4.3
>> Candidate multilib: .;@m64
>> Candidate multilib: 32;@m32
>> Selected multilib: .;@m64
>>
>> Best regards,
>> Martin
>>
>> _______________________________________________
>> cfe-dev mailing list
>> cfe-dev at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>>
>
>


-- 
Alexey Samsonov, MSK
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