bson_iter_overwrite_bool (bson_iter_t *iter, /* IN */
                          bool value)        /* IN */
{
   BSON_ASSERT (iter);

   if (ITER_TYPE (iter) == BSON_TYPE_BOOL) {
      memcpy ((void *) (iter->raw + iter->d1), &value, 1);
   }
}

The product reads data past the end, or before the beginning, of the intended buffer.