[LLVMdev] DataFlowSanitizer only for Linux

[Juan Ceasar]

Aha!  Thank you!  Works perfectly...

And for OS X, at least on my 10.10.3 system, I had to build OpenSSL via:

COV_FLAGS="-fsanitize-coverage=edge,indirect-calls"
./Configure darwin64-x86_64-cc zlib threads shared &&
  make -j 8 CC="/usr/local/bin/clang -g -fsanitize=address $COV_FLAGS"

and then

/usr/local/bin/clang++ -g  -fsanitize=address handshake_fuzz.o
openssl-1.0.1f/libcrypto.a openssl-1.0.1f/libssl.a Fuzzer*.o -lz

Just in case you wanted to update the wiki...
Because OpenSSL was being finicky I had missed the sanitization args on a
rebuild just as you said :-)

Thanks again.  I'm going to look into the DFSan lib for OS X next week.
Have a good one!



On Fri, Jul 10, 2015 at 2:44 PM, Kostya Serebryany <kcc at google.com> wrote:

> The log indicates that you did not add the -fsanitize-coverage=... flags.
> E.g. -fsanitize-coverage=edge,indirect-calls,8bit-counters
>
> On Fri, Jul 10, 2015 at 11:40 AM, Juan Ceasar <juan.d.ceasar at gmail.com>
> wrote:
>
>> Kostya,
>>
>> I took a quick stab at patching libFuzzer for Apple, but so far I'm
>> thinking something else is incorrect.  Patch is attached but when I went to
>> reproduce the examples, the toy example went fine, but with PCRE and
>> Heartbleed I noticed the coverage statistics were pretty poor, and didn't
>> find anything.  Admittedly I moved onto Heartbleed pretty quickly so PCRE
>> probably isn't the best judge.  But here's a sample log from the Heartbleed
>> session (they were all similar):
>>
>> $ cat fuzz-11.log
>>
>> Seed: 3157140177
>>
>> SetTimer 601
>>
>> PreferSmall: 1
>>
>> #0 READ   cov 0 bits 0 units 1 exec/s 0
>>
>> #1 pulse  cov 0 bits 0 units 1 exec/s 0
>>
>> #1 INITED cov 0 bits 0 units 0 exec/s 0
>>
>> Done 1 runs in 4 second(s)
>>
>>
>> Any thoughts?  Obviously I'm not attached to anything in the patch, just
>> trying to get something working on OS X.
>>
>>
>>
>> On Wed, Jul 8, 2015 at 11:42 AM, Juan Ceasar <juan.d.ceasar at gmail.com>
>> wrote:
>>
>>> Thanks!  I'll give it a shot and see what I can do to give some patches
>>> back.
>>>
>>> On Wed, Jul 8, 2015 at 9:42 AM, Alexander Potapenko <glider at google.com>
>>> wrote:
>>>
>>>> FWIW see also
>>>> http://lists.cs.uiuc.edu/pipermail/cfe-dev/2015-June/043301.html
>>>> As far as I understand DFSan functionality isn't required for
>>>> libFuzzer to work, so it should be safe to disable DFSan support on
>>>> Mac.
>>>>
>>>> On Wed, Jul 8, 2015 at 7:45 AM, Kostya Serebryany <kcc at google.com>
>>>> wrote:
>>>> > +pcc , glider
>>>> >
>>>> > On Mon, Jul 6, 2015 at 12:59 PM, Juan Ceasar <juan.d.ceasar at gmail.com
>>>> >
>>>> > wrote:
>>>> >>
>>>> >> Afternoon,
>>>> >>
>>>> >> I had an issue with trying to link a program with the
>>>> DataFlowSanitizer
>>>> >> functionality, this is from the libFuzzer project, and I was seeing:
>>>> >>
>>>> >> clang++ -fsanitize=address -fsanitize-coverage=edge test_fuzzer.cc
>>>> >> Fuzzer*.o
>>>> >>
>>>> >> Undefined symbols for architecture x86_64:
>>>> >>
>>>> >>   "_dfsan_create_label", referenced from:
>>>> >>
>>>> >>       fuzzer::TraceState::DFSanCmpCallback(unsigned long, unsigned
>>>> long,
>>>> >> unsigned long, unsigned long long, unsigned long long, unsigned
>>>> short,
>>>> >> unsigned short) in FuzzerTraceState.o
>>>> >>
>>>> >>       fuzzer::Fuzzer::InitializeTraceState() in FuzzerTraceState.o
>>>> >>
>>>> >>   "_dfsan_get_label_info", referenced from:
>>>> >>
>>>> >>       fuzzer::TraceState::GetLabelRange(unsigned short) in
>>>> >> FuzzerTraceState.o
>>>> >>
>>>> >>   .....
>>>> >>
>>>> >> But then looking at the docs:
>>>> >> http://clang.llvm.org/docs/DataFlowSanitizer.html
>>>> >>
>>>> >> It appears that this is only supported under Linux?  Is that right?
>>>> >>
>>>> >
>>>> > Correct. AFAICT, DFSan was only tested on Linux.
>>>> > It is quite hard to make it work on Mac because there are too many
>>>> closed
>>>> > source libraries there.
>>>> > Nothing impossible though -- it's just that nobody has worked on it.
>>>> >
>>>> > libFuzzer was also never tested on Mac, but I think it should be
>>>> trivial to
>>>> > make it work there.
>>>> > I suspect that the errors you see are caused by the weak function
>>>> > declarations which don't (???) work on Mac.
>>>> > You'll need to #ifdef the weak functions on Mac somehow. Patches and
>>>> Mac
>>>> > buildbots are welcome :)
>>>> >
>>>> > --kcc
>>>> >
>>>> >>
>>>> >>
>>>> >>
>>>> >> _______________________________________________
>>>> >> LLVM Developers mailing list
>>>> >> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>>> >> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>> >>
>>>> >
>>>>
>>>>
>>>>
>>>> --
>>>> Alexander Potapenko
>>>> Software Engineer
>>>>
>>>> Google Germany GmbH
>>>> Dienerstraße 12
>>>> 80331 München
>>>>
>>>
>>>
>>
>
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