linux-kernel - [PATCH 1/2] regmap: fix NULL pointer dereference in regmap_name_read

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Date:   Tue, 23 Jan 2018 16:53:42 -0600
From:   David Lechner <david@...hnology.com>
To:     linux-kernel@...r.kernel.org
Cc:     David Lechner <david@...hnology.com>,
        Mark Brown <broonie@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [PATCH 1/2] regmap: fix NULL pointer dereference in regmap_name_read_file()

This fixes a possible NULL pointer dereference oops in
regmap_name_read_file() when the regmap does not have a device
associated with it.

Signed-off-by: David Lechner <david@...hnology.com>
---
 drivers/base/regmap/regmap-debugfs.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index 36ce351..0df7379 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -40,6 +40,7 @@ static ssize_t regmap_name_read_file(struct file *file,
 				     loff_t *ppos)
 {
 	struct regmap *map = file->private_data;
+	const char *name = NULL;
 	int ret;
 	char *buf;
 
@@ -47,7 +48,10 @@ static ssize_t regmap_name_read_file(struct file *file,
 	if (!buf)
 		return -ENOMEM;
 
-	ret = snprintf(buf, PAGE_SIZE, "%s\n", map->dev->driver->name);
+	if (map->dev && map->dev->driver)
+		name = map->dev->driver->name;
+
+	ret = snprintf(buf, PAGE_SIZE, "%s\n", name);
 	if (ret < 0) {
 		kfree(buf);
 		return ret;
-- 
2.7.4