[PATCH AUTOSEL 3.18 47/61] hwmon: (lm80) fix a missing check of the status of SMBus read

[Sasha Levin]

From: Kangjie Lu <k...@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 <k...@umn.edu>
[groeck: One variable for return values is enough]
Signed-off-by: Guenter Roeck <li...@roeck-us.net>
Signed-off-by: Sasha Levin <sas...@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 4bcd9b882948..47ddae6b7038 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