[LLVMdev] DataFlowSanitizer only for Linux (original) (raw)

Juan Ceasar juan.d.ceasar at gmail.com
Fri Jul 10 11:40:52 PDT 2015

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 testfuzzer.cc >> Fuzzer*.o >> >> Undefined symbols for architecture x8664: >> >> "dfsancreatelabel", 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 >> >> "dfsangetlabelinfo", 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 >> >

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