In order to build the fuzzer one needs to build HarfBuzz and
harfbuzz/test/fuzzing/hb-fuzzer.cc with:
- Using the most recent Clang
- With -fsanitize=address (or =undefined, or a combination)
- With -fsanitize-coverage=edge[,8bit-counters,trace-cmp]
- With various defines that limit worst case exponential behavior.
See FUZZING_CPPFLAGS in harfbuzz/src/Makefile.am for the list.
- link against libFuzzer
To run the fuzzer one needs to first obtain a test corpus as a directory
containing interesting fonts. A good starting point is inside
harfbuzz/test/shaping/fonts/fonts/.
Then, run the fuzzer like this:
./hb-fuzzer -max_len=2048 CORPUS_DIR
Where max_len specifies the maximal length of font files to handle.
The smaller the faster.
For more details consult the following locations:
- http://llvm.org/docs/LibFuzzer.html or
- https://github.com/google/libfuzzer-bot/tree/master/harfbuzz
- https://github.com/behdad/harfbuzz/issues/139
