[PATCH v2] media: v4l2-core: Drop manual fwnode_handle_put() via scope-based cleanup

[Biren Pandya]

v4l2_subdev_get_fwnode_pad_1_to_1() acquires a fwnode reference and drops
it via fwnode_handle_put() before calling device_match_fwnode(). This
requires manual lifecycle management.

Simplify the function by converting the local fwnode variable to use the
__free(fwnode_handle) scope-based cleanup macro.

Signed-off-by: Biren Pandya <birenpandya@xxxxxxxxx>
---
Changes in v2:
- Updated the commit message to remove the "Use-After-Free" language,
  as there is no vulnerability in practice.
- Adjusted the implementation to declare `struct fwnode_handle *fwnode`
  directly at the point of initialization, rather than at the top of the
  block, conforming to recommended usage.
- Renamed the patch subject to better reflect the true nature of the change.
- Link to v1: https://lore.kernel.org/all/20260616092516.46339-1-birenpandya@xxxxxxxxx/

Hi Laurent,

My sincere apologies for the mailing list noise earlier. That duplicate 
submission was an accidental misfire while I was adjusting my `git send-email`
scripts, and I deeply apologize for the lack of versioning and threading. 
I am still getting up to speed with the subsystem's submission workflow! 
Here is the correctly formatted v2 addressing Sakari's feedback.

 drivers/media/v4l2-core/v4l2-subdev.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index e6b133ef7850..806b059410ce 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -1243,7 +1243,8 @@ const struct v4l2_file_operations v4l2_subdev_fops = {
 int v4l2_subdev_get_fwnode_pad_1_to_1(struct media_entity *entity,
 				      struct fwnode_endpoint *endpoint)
 {
-	struct fwnode_handle *fwnode __free(fwnode_handle) = NULL;
+	struct fwnode_handle *fwnode __free(fwnode_handle) =
+		fwnode_graph_get_port_parent(endpoint->local_fwnode);
 	struct v4l2_subdev *sd;
 
 	if (!is_media_entity_v4l2_subdev(entity))
@@ -1251,8 +1252,6 @@ int v4l2_subdev_get_fwnode_pad_1_to_1(struct media_entity *entity,
 
 	sd = media_entity_to_v4l2_subdev(entity);
 
-	fwnode = fwnode_graph_get_port_parent(endpoint->local_fwnode);
-
 	if (device_match_fwnode(sd->dev, fwnode))
 		return endpoint->port;
 
-- 
2.50.1 (Apple Git-155)