[LLVMdev] DataFlowSanitizer only for Linux

[Kostya Serebryany]

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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