Variant HHVM_FUNCTION(mcrypt_generic_init, const Resource& td,
                                           const String& key,
                                           const String& iv) {
  auto pm = get_valid_mcrypt_resource(td);
  if (!pm) {
    return false;
  }

  int max_key_size = mcrypt_enc_get_key_size(pm->m_td);
  int iv_size = mcrypt_enc_get_iv_size(pm->m_td);

  if (key.empty()) {
    raise_warning("Key size is 0");
  }

  unsigned char *key_s = (unsigned char *)malloc(key.size());
  memset(key_s, 0, key.size());

  unsigned char *iv_s = (unsigned char *)malloc(iv_size + 1);
  memset(iv_s, 0, iv_size + 1);

  int key_size;
  if (key.size() > max_key_size) {
    raise_warning("Key size too large; supplied length: %ld, max: %d",
                    key.size(), max_key_size);
    key_size = max_key_size;
  } else {
    key_size = key.size();
  }
  memcpy(key_s, key.data(), key.size());

  if (iv.size() != iv_size) {
    raise_warning("Iv size incorrect; supplied length: %ld, needed: %d",
                    iv.size(), iv_size);
  }
  memcpy(iv_s, iv.data(), std::min<int64_t>(iv_size, iv.size()));

  mcrypt_generic_deinit(pm->m_td);
  int result = mcrypt_generic_init(pm->m_td, key_s, key_size, iv_s);

  /* If this function fails, close the mcrypt module to prevent crashes
   * when further functions want to access this resource */
  if (result < 0) {
    pm->close();
    switch (result) {
    case -3:
      raise_warning("Key length incorrect");
      break;
    case -4:
      raise_warning("Memory allocation error");
      break;
    case -1:
    default:
      raise_warning("Unknown error");
      break;
    }
  } else {
    pm->m_init = true;
  }

  free(iv_s);
  free(key_s);
  return result;
}
The software performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control.