Fuzzing with afl++

[magv]

Hi, all. So I got FORM fuzzing to work with afl++, and I'd like to consult with you on how to proceed. The scripts are in form-fuzz, with some description of how to run them. The workflow is that:

1. We build FORM multiple times with different sanitizers.
2. We launch one fuzzer per sanitizer, and probably a few more (see the afl docs on this).
3. We wait a bit, and then investigate the crashing files in /tmp/form-fuzz/out/*/crashes/.

There is, of course, much more to be done to make this effective and efficient (i.e. the persistent mode).

Currently I'm already looking at hundreds of "crashing" files, most of which are either syntax errors, or strange ASAN-related bugs. Some work needs to help the fuzzer distinguish between expected crashes and actual problems. Not sure what the total scope of this work is at the moment.