From:   Fabio Estevam <festevam@gmail.com>
To:     broonie@kernel.org
Cc:     matthias.schiffer@ew.tq-group.com, linux-kernel@vger.kernel.org,
        Fabio Estevam <festevam@gmail.com>
Subject: [PATCH v2] regmap: debugfs: Free debugfs_name buffer after usage
Date:   Thu,  6 Jan 2022 14:50:19 -0300
Message-Id: <20220106175019.3116389-1-festevam@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The following error message is seen when booting an imx6q-sabresd:

debugfs: Directory 'dummy-iomuxc-gpr@20e0000' with parent 'regmap' already present!

The reason for the duplicate name is that map->debugfs_name is never freed,
which can cause a directory to be created with the same name used in the
previous debugfs entry allocation.

Fix this problem by freeing map->debugfs_name and setting it to NULL
after its usage.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
---
Changes since v1:
- Avoid use after free (Mark).

 drivers/base/regmap/regmap-debugfs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index ad684d37c2da..e1017ca65be0 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -605,6 +605,9 @@ void regmap_debugfs_init(struct regmap *map)
 
 	map->debugfs = debugfs_create_dir(name, regmap_debugfs_root);
 
+	kfree(map->debugfs_name);
+	map->debugfs_name = NULL;
+
 	debugfs_create_file("name", 0400, map->debugfs,
 			    map, &regmap_name_fops);
 
-- 
2.25.1