WiFi stack fuzzing status report

Hi All,

PR: https://github.com/google/syzkaller/pull/5992

This PR aims to improve the support of Syzkaller on FreeBSD. Based on 
the existing WiFi fuzzer designed for Linux, we drafted a new WiFi 
fuzzer for FreeBSD. We used wtap, a virtual wifi driver for testing, to 
support WiFi fuzzing.

The coverage of this fuzzer (~2000 ~LoC) is quite low compared to the 
Linux one (~20000 LoC). There may be some room for improvement. However, 
Syzkaller doesn't fully support all coverage features on FreeBSD for 
now. It can only check how many line of code but not which part of code.

For a more detailed setup, check out my write-up:
https://hackmd.io/byPgVrEwRWSA5LKc56-30Q

Feel free to reply to this thread or comment on the PR above if you have 
any questions.

Best Regards,
Jian-Lin