[cfe-dev] i386 -faddress-sanitizer

[Carsten Mattner]

On Sat, Oct 20, 2012 at 3:46 PM, Kostya Serebryany <kcc at google.com> wrote:
>
>
> On Sat, Oct 20, 2012 at 3:15 PM, Carsten Mattner <carstenmattner at gmail.com>
> wrote:
>>
>> On Fri, Oct 19, 2012 at 9:07 AM, Kostya Serebryany <kcc at google.com> wrote:
>> >
>> >
>> > On Fri, Oct 19, 2012 at 12:50 AM, Carsten Mattner
>> > <carstenmattner at gmail.com>
>> > wrote:
>> >>
>> >> On Thu, Oct 18, 2012 at 6:27 PM, Kostya Serebryany <kcc at google.com>
>> >> wrote:
>> >> >
>> >> >
>> >> > On Thu, Oct 18, 2012 at 8:19 PM, Carsten Mattner
>> >> > <carstenmattner at gmail.com>
>> >> > wrote:
>> >> >>
>> >> >> On Thu, Oct 18, 2012 at 5:41 PM, Alexander Potapenko
>> >> >> <glider at google.com>
>> >> >> wrote:
>> >> >> > You have two issues here then.
>> >> >> > First, for some reason the linker doesn't like the unresolved
>> >> >> > calls
>> >> >> > to
>> >> >> > ASan runtime in your shared object. Can you please attach the full
>> >> >> > command line used to invoke the linker (feel free to obfuscate the
>> >> >> > file names if needed, but please keep the flags).
>> >> >>
>> >> >> clang c_src/<PROJECT>.o -lstdc++ -v -faddress-sanitizer
>> >> >>   -shared
>> >> >>   -L/usr/local/lib/erlang/lib/erl_interface-3.7.8/lib
>> >> >>   -lerl_interface -lei -o priv/<PROJECT>.so
>> >> >> clang version 3.2 (http://llvm.org/git/clang.git
>> >> >> 278eafa2cd8296f8128d13c6466a0ace3d03a872)
>> >> >> (http://llvm.org/git/llvm.git
>> >> >> 2360b7ad99eedecaae512373e7be49c2143550cf)
>> >> >> Target: i386-pc-linux-gnu
>> >> >> Thread model: posix
>> >> >>  "/usr/bin/ld" --eh-frame-hdr -m elf_i386 -shared -o
>> >> >> priv/<PROJECT>.so
>> >> >>  /usr/lib/gcc/i686-pc-linux-gnu/4.7.2/../../../crti.o
>> >> >>  /usr/lib/gcc/i686-pc-linux-gnu/4.7.2/crtbeginS.o
>> >> >>  -L/usr/local/lib/erlang/lib/erl_interface-3.7.8/lib
>> >> >>  -L/usr/lib/gcc/i686-pc-linux-gnu/4.7.2
>> >> >>  -L/usr/lib/gcc/i686-pc-linux-gnu/4.7.2/../../.. -L/lib -L/usr/lib
>> >> >>  c_src/<PROJECT>.o -lstdc++
>> >> >>  -lerl_interface -lei -lgcc --as-needed -lgcc_s
>> >> >>  --no-as-needed -lc -lgcc --as-needed -lgcc_s --no-as-needed
>> >> >>  /usr/lib/gcc/i686-pc-linux-gnu/4.7.2/crtendS.o
>> >> >>  /usr/lib/gcc/i686-pc-linux-gnu/4.7.2/../../../crtn.o
>> >> >
>> >> >
>> >> > Hm. I don't see any reason for the failure here... Anyone?
>> >>
>> >> Is the probably special handling for .so files that automatically
>> >> prevents linking in asan.a?
>> >
>> >
>> >
>> > In the clang driver we check what is being linked and pass libasan.a to
>> > ld
>> > only if the final executable is being linked.
>> > So, a shared library just doesn't get linked with asan.a, but it still
>> > has
>> > __asan_report_* callbacks,
>> > which may cause link errors if you are using -Wl,-z,defs (or something
>> > similar).
>> > Looks like you have resolved the problem, right?
>>
>> Yes after being told which parts need to be built with or without
>> -faddress-sanitizer it was simple to use.
>>
>> > Let us know if the tool works for your case (and if you find bugs in
>> > Erlang
>> > :)
>>
>> Is runtime abort upon detecting an error the expected effect?
>
>
> Yes, asan exits on the first error, this is by design.
> (hm, I guess we need to make a FAQ entry about this... Will do.)
>
>>
>> Anything else?
>>
>> > BTW, I've extended the docs a bit:
>> > http://clang.llvm.org/docs/AddressSanitizer.html#usage
>>
>> Thanks. I believe you should explicity document that LDFLAGS
>> when building a shared object should not contain -faddress-sanitizer
>
>
> LDFLAGS may contain  -faddress-sanitizer when building DSOs --
> it won't hurt but it will be ignored.

More correct would be to say "it's meaningless to link a shared
object with -faddress-sanitizer because pnly the runtime loading
the shared object has to be linked with -faddress-sanitizer".