on_unregister_handler(TCMUService1HandlerManager1 *interface,
		      GDBusMethodInvocation *invocation,
		      gchar *subtype,
 		      gpointer user_data)
 {
 	struct tcmur_handler *handler = find_handler_by_subtype(subtype);
	struct dbus_info *info = handler->opaque;
 
 	if (!handler) {
 		g_dbus_method_invocation_return_value(invocation,
			g_variant_new("(bs)", FALSE,
				      "unknown subtype"));
		return TRUE;
	}
	dbus_unexport_handler(handler);
	tcmur_unregister_handler(handler);
	g_bus_unwatch_name(info->watcher_id);
	g_free(info);
	g_free(handler);
	g_dbus_method_invocation_return_value(invocation,
		g_variant_new("(bs)", TRUE, "succeeded"));
	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.