test_bson_append_null (void)
{
   bson_t *b;
   bson_t *b2;

   b = bson_new ();
   BSON_ASSERT (bson_append_null (b, "hello", -1));
   b2 = get_bson ("test18.bson");
   BSON_ASSERT_BSON_EQUAL (b, b2);
   bson_destroy (b);
   bson_destroy (b2);
}

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