linux-kernel - Applied "regmap: Allow missing device in regmap_name_read

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Message-Id: <E1eo6kJ-0003E2-GT@debutante>
Date:   Tue, 20 Feb 2018 12:10:07 +0000
From:   Mark Brown <broonie@...nel.org>
To:     David Lechner <david@...hnology.com>
Cc:     Mark Brown <broonie@...nel.org>, linux-kernel@...r.kernel.org,
        Mark Brown <broonie@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Subject: Applied "regmap: Allow missing device in regmap_name_read_file()" to the regmap tree

The patch

   regmap: Allow missing device in regmap_name_read_file()

has been applied to the regmap tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From 12ae3808c160b7be0de3c633ac4cbe8c5f2937bf Mon Sep 17 00:00:00 2001
From: David Lechner <david@...hnology.com>
Date: Mon, 19 Feb 2018 15:43:01 -0600
Subject: [PATCH] regmap: Allow missing device 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. For example syscon regmaps retrieved with
syscon_regmap_lookup_by_compatible() don't have a device.

Signed-off-by: David Lechner <david@...hnology.com>
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 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 f3266334063e..7eb512ba2828 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 = "nodev";
 	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;
-- 
2.16.1