snappy_uncompress_fuzzer.cc

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// libFuzzer harness for fuzzing snappy's decompression code.

#include <cassert>
#include <cstddef>
#include <cstdint>
#include <string>

#include "snappy.h"

// Entry point for LibFuzzer.
extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
  std::string input(reinterpret_cast<const char*>(data), size);

  // Avoid self-crafted decompression bombs.
  size_t uncompressed_size;
  constexpr size_t kMaxUncompressedSize = 1 << 20;
  bool get_uncompressed_length_succeeded = snappy::GetUncompressedLength(
      input.data(), input.size(), &uncompressed_size);
  if (!get_uncompressed_length_succeeded ||
      (uncompressed_size > kMaxUncompressedSize)) {
    return 0;
  }

  std::string uncompressed;
  // The return value of snappy::Uncompress() is ignored because decompression
  // will fail on invalid inputs.
  snappy::Uncompress(input.data(), input.size(), &uncompressed);
  return 0;
}