device property: fix of node refcount leak in fwnode_graph_get_next_e…

…ndpoint()

The 'parent' returned by fwnode_graph_get_port_parent()
with refcount incremented when 'prev' is not NULL, it
needs be put when finish using it.

Because the parent is const, introduce a new variable to
store the returned fwnode, then put it before returning
from fwnode_graph_get_next_endpoint().

Fixes: b5b41ab ("device property: Check fwnode->secondary in fwnode_graph_get_next_endpoint()")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-and-tested-by: Daniel Scally <djrscally@gmail.com>
Link: https://lore.kernel.org/r/20221123022542.2999510-1-yangyingliang@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/property.c

@@ -997,26 +997,32 @@ struct fwnode_handle *
 fwnode_graph_get_next_endpoint(const struct fwnode_handle *fwnode,
 			       struct fwnode_handle *prev)
 {
+	struct fwnode_handle *ep, *port_parent = NULL;
 	const struct fwnode_handle *parent;
-	struct fwnode_handle *ep;
 
 	/*
 	 * If this function is in a loop and the previous iteration returned
 	 * an endpoint from fwnode->secondary, then we need to use the secondary
 	 * as parent rather than @fwnode.
 	 */
-	if (prev)
-		parent = fwnode_graph_get_port_parent(prev);
-	else
+	if (prev) {
+		port_parent = fwnode_graph_get_port_parent(prev);
+		parent = port_parent;
+	} else {
 		parent = fwnode;
+	}
 	if (IS_ERR_OR_NULL(parent))
 		return NULL;
 
 	ep = fwnode_call_ptr_op(parent, graph_get_next_endpoint, prev);
 	if (ep)
-		return ep;
+		goto out_put_port_parent;
+
+	ep = fwnode_graph_get_next_endpoint(parent->secondary, NULL);
 
-	return fwnode_graph_get_next_endpoint(parent->secondary, NULL);
+out_put_port_parent:
+	fwnode_handle_put(port_parent);
+	return ep;
 }
 EXPORT_SYMBOL_GPL(fwnode_graph_get_next_endpoint);