A Tour into Fuzzing

Fuzzing

parse_request

void parse_message(const request_header *h, const uint8_t *data) {
  uint8_t msg[64];

  // On release this is no-op

  // Critical section
  // Remove conditional for unchecked bounds on memcpy
  // Discoverable via fuzzing
  // if (h->length < 64) {
  std::memcpy(msg, data, h->length);
  // }
}

To test a payload use

cat <payload> | nc localhost 9000
# or
echo <payload> -ne | nc localhost 9000

Use xxd for getting encode/decode the payload

Tools

libFuzzer

Set ENABLE_FUZZING=libFuzzer CMake variable or use x64-linux-libFuzzer preset.

fuzztest

Set ENABLE_FUZZING=[fuzztest|fuzztest-unit] CMake variable or use x64-linux-fuzztest[-unit] preset.