linux-kernel - [PATCH v2] media: v4l2-core: Fix a potential resource leak in v4l2_fwnode_parse

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Date:   Wed, 14 Jun 2023 20:31:05 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        linux-media@...r.kernel.org
Subject: [PATCH v2] media: v4l2-core: Fix a potential resource leak in v4l2_fwnode_parse_link()

If fwnode_graph_get_remote_endpoint() fails, 'fwnode' is known to be NULL,
so fwnode_handle_put() is a no-op.

Release the reference taken from a previous fwnode_graph_get_port_parent()
call instead.

Also handle fwnode_graph_get_port_parent() failures.

In order to fix these issues, add an error handling path to the function
and the needed gotos.

Fixes: ca50c197bd96 ("[media] v4l: fwnode: Support generic fwnode for parsing standardised properties")
Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
v2: - Handle fwnode_graph_get_port_parent() errors   [Sakari Ailus <sakari.ailus@...ux.intel.com>]
    - Rephrase the commit log

v1: https://lore.kernel.org/all/2ddd10ec9e009bbb85518355f1e09e1ecd349925.1685340968.git.christophe.jaillet@wanadoo.fr/
---
 drivers/media/v4l2-core/v4l2-fwnode.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
index 049c2f2001ea..4fa9225aa3d9 100644
--- a/drivers/media/v4l2-core/v4l2-fwnode.c
+++ b/drivers/media/v4l2-core/v4l2-fwnode.c
@@ -568,19 +568,29 @@ int v4l2_fwnode_parse_link(struct fwnode_handle *fwnode,
 	link->local_id = fwep.id;
 	link->local_port = fwep.port;
 	link->local_node = fwnode_graph_get_port_parent(fwnode);
+	if (!link->local_node)
+		return -ENOLINK;
 
 	fwnode = fwnode_graph_get_remote_endpoint(fwnode);
-	if (!fwnode) {
-		fwnode_handle_put(fwnode);
-		return -ENOLINK;
-	}
+	if (!fwnode)
+		goto err_put_local_node;
 
 	fwnode_graph_parse_endpoint(fwnode, &fwep);
 	link->remote_id = fwep.id;
 	link->remote_port = fwep.port;
 	link->remote_node = fwnode_graph_get_port_parent(fwnode);
+	if (!link->remote_node)
+		goto err_put_remote_endpoint;
 
 	return 0;
+
+err_put_remote_endpoint:
+	fwnode_handle_put(fwnode);
+
+err_put_local_node:
+	fwnode_handle_put(link->local_node);
+
+	return -ENOLINK;
 }
 EXPORT_SYMBOL_GPL(v4l2_fwnode_parse_link);
 
-- 
2.34.1