linux-kernel - [PATCH 3.16 086/178] hwmon: (asus_atk0110) fix uninitialized data access

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Message-ID: <lsq.1500213406.1524150@decadent.org.uk>
Date:   Sun, 16 Jul 2017 14:56:46 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Luca Tettamanti" <kronos.it@...il.com>,
        "Guenter Roeck" <linux@...ck-us.net>,
        "Arnd Bergmann" <arnd@...db.de>
Subject: [PATCH 3.16 086/178] hwmon: (asus_atk0110) fix uninitialized data
 access

3.16.46-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Arnd Bergmann <arnd@...db.de>

commit a2125d02443e9a4e68bcfd9f8004fa23239e8329 upstream.

The latest gcc-7 snapshot adds a warning to point out that when
atk_read_value_old or atk_read_value_new fails, we copy
uninitialized data into sensor->cached_value:

drivers/hwmon/asus_atk0110.c: In function 'atk_input_show':
drivers/hwmon/asus_atk0110.c:651:26: error: 'value' may be used uninitialized in this function [-Werror=maybe-uninitialized]

Adding an error check avoids this. All versions of the driver
are affected.

Fixes: 2c03d07ad54d ("hwmon: Add Asus ATK0110 support")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
Reviewed-by: Luca Tettamanti <kronos.it@...il.com>
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/hwmon/asus_atk0110.c | 3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/hwmon/asus_atk0110.c
+++ b/drivers/hwmon/asus_atk0110.c
@@ -646,6 +646,9 @@ static int atk_read_value(struct atk_sen
 		else
 			err = atk_read_value_new(sensor, value);
 
+		if (err)
+			return err;
+
 		sensor->is_valid = true;
 		sensor->last_updated = jiffies;
 		sensor->cached_value = *value;