[PATCH AUTOSEL 4.14 141/170] hwmon: (lm80) fix a missing check of the status of SMBus read

Sasha Levin
2019-01-28T16:53:37Z

From: Kangjie Lu <kjlu@umn.edu>

[ Upstream commit c9c63915519b1def7043b184680f33c24cd49d7b ]

If lm80_read_value() fails, it returns a negative number instead of the
correct read data. Therefore, we should avoid using the data if it
fails.

The fix checks if lm80_read_value() fails, and if so, returns with the
error number.

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
[groeck: One variable for return values is enough]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/hwmon/lm80.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/hwmon/lm80.c b/drivers/hwmon/lm80.c
index 08e3945a6fbf..04f9df0d2341 100644
--- a/drivers/hwmon/lm80.c
+++ b/drivers/hwmon/lm80.c
@@ -360,9 +360,11 @@ static ssize_t set_fan_div(struct device *dev, struct device_attribute *attr,
struct i2c_client *client = data->client;
unsigned long min, val;
u8 reg;
- int err = kstrtoul(buf, 10, &val);
- if (err < 0)
- return err;
+ int rv;
+
+ rv = kstrtoul(buf, 10, &val);
+ if (rv < 0)
+ return rv;

/* Save fan_min */
mutex_lock(&data->update_lock);
@@ -390,8 +392,11 @@ static ssize_t set_fan_div(struct device *dev, struct device_attribute *attr,
return -EINVAL;
}

- reg = (lm80_read_value(client, LM80_REG_FANDIV) &
- ~(3 << (2 * (nr + 1)))) | (data->fan_div[nr] << (2 * (nr + 1)));
+ rv = lm80_read_value(client, LM80_REG_FANDIV);
+ if (rv < 0)
+ return rv;
+ reg = (rv & ~(3 << (2 * (nr + 1))))
+ | (data->fan_div[nr] << (2 * (nr + 1)));
lm80_write_value(client, LM80_REG_FANDIV, reg);

/* Restore fan_min */
--
2.19.1