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

Juan Ceasar juan.d.ceasar at gmail.com
Fri Jul 10 13:02:05 PDT 2015

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 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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