fuzz_pybser.py

#!/usr/bin/env python

import sys

import afl

from pywatchman import pybser

afl.start()

try:
    pybser.loads(sys.stdin.read())
except BaseException as e:
    if type(e) != RuntimeError:
        raise

Here is the corpus of examples running this for a couple minutes produced:

'\x00\x01'
'\x00\x01\x05'
'\x00\x01\x06'
'\x00\x01\x04'
'\x00\x01\x03'
'\x00\x01\x04\x01\x00\x00'
'\x00\x01\x04\x01\x00\x01'
'\x00\x01\x04\x01\x00\x02'
'\x00\x01\x04\x01\x00\x04'
'\x00\x01\x03\x00'

Example error coming from this:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "pywatchman/pybser.py", line 293, in loads
    return _bser_loads_recursive(buf, pos)[0]
  File "pywatchman/pybser.py", line 269, in _bser_loads_recursive
    return _bunser_string(buf, pos)
  File "pywatchman/pybser.py", line 211, in _bunser_string
    str_len, pos = _bunser_int(buf, pos + 1)
  File "pywatchman/pybser.py", line 191, in _bunser_int
    int_type = buf[pos]
IndexError: string index out of range