bool smbXcli_conn_is_connected(struct smbXcli_conn *conn)
{
	if (conn == NULL) {
		return false;
	}

	if (conn->sock_fd == -1) {
		return false;
	}

	return true;
}

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.