examples/ubsan_function_ptr_fuzz_test.cc

// Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// A fuzz target that calls a function through a pointer of a mismatched type.
// This is detected by UBSAN's function check and requires the UBSAN C++
// runtime.

#include <cstddef>
#include <cstdint>

int parse_data(const uint16_t *data) {
  return data[0] + data[1];
}

int (*mistyped_function_pointer)(const uint8_t *data);

extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
  if (size < 2) {
    return 0;
  }
  mistyped_function_pointer =
      reinterpret_cast<int (*)(const uint8_t *)>(parse_data);
  mistyped_function_pointer(data);
  return 0;
}