Fixed the issue that custom mutator function is not invoked

[friendlyJLee]

I tried custom mutator functionality as readme, and implemented the "dll_muate_testcase" function. However, I found my custom mutator was never called, so I looked at the source code of winafl and found a minor bug in the following code.

  // Prefer a custom mutator that accepts the performance score as an energy value.
  if (dll_mutate_testcase_with_energy_ptr)
    if (dll_mutate_testcase_with_energy_ptr(argv, in_buf, len, perf_score, common_fuzz_stuff))
      goto abandon_entry;
  else if (dll_mutate_testcase_ptr)
    if (dll_mutate_testcase_ptr(argv, in_buf, len, common_fuzz_stuff))
      goto abandon_entry;

It seems like WinAFL intends to call a custom mutator function if either 'dll_mutate_testcase_with_energy' or 'dll_mutate_testcase' function is given by a user. However, "dll_mutate_testcase" is never called if a user only implements "dll_muate_testcase" without implementing "dll_mutate_testcase_with_energy" because of if-else priority. Making the above code clear, it will be the following.

 if (dll_mutate_testcase_with_energy_ptr) {
      if (dll_mutate_testcase_with_energy_ptr(argv, in_buf, len, perf_score, common_fuzz_stuff))
          goto abandon_entry;
      else if (dll_mutate_testcase_ptr)
          if (dll_mutate_testcase_ptr(argv, in_buf, len, common_fuzz_stuff))
              goto abandon_entry;
}

So, I have fixed the above issue adding brackets, and checked to work well.

[ifratric]

Argh, you are right! Thanks for spotting and fixing!