_dbus_atomic_dec (DBusAtomic *atomic)
{
#if DBUS_USE_SYNC
  return __sync_sub_and_fetch(&atomic->value, 1)+1;
#else
  dbus_int32_t res;

  _DBUS_LOCK (atomic);
  res = atomic->value;
  atomic->value -= 1;
  _DBUS_UNLOCK (atomic);
  return res;
#endif
}

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.