hwmon: (lm80) fix a missing check of bus read in lm80 probe

BugLink: https://bugs.launchpad.net/bugs/1818813

[ Upstream commit 9aa3aa15 ]

In lm80_probe(), if lm80_read_value() fails, it returns a negative
error number which is stored to data->fan[f_min] and will be further
used. We should avoid using the data if the read 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>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/hwmon/lm80.c

@@ -628,6 +628,7 @@ static int lm80_probe(struct i2c_client *client,
 	struct device *dev = &client->dev;
 	struct device *hwmon_dev;
 	struct lm80_data *data;
+	int rv;
 
 	data = devm_kzalloc(dev, sizeof(struct lm80_data), GFP_KERNEL);
 	if (!data)
@@ -640,8 +641,14 @@ static int lm80_probe(struct i2c_client *client,
 	lm80_init_client(client);
 
 	/* A few vars need to be filled upon startup */
-	data->fan[f_min][0] = lm80_read_value(client, LM80_REG_FAN_MIN(1));
-	data->fan[f_min][1] = lm80_read_value(client, LM80_REG_FAN_MIN(2));
+	rv = lm80_read_value(client, LM80_REG_FAN_MIN(1));
+	if (rv < 0)
+		return rv;
+	data->fan[f_min][0] = rv;
+	rv = lm80_read_value(client, LM80_REG_FAN_MIN(2));
+	if (rv < 0)
+		return rv;
+	data->fan[f_min][1] = rv;
 
 	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 							   data, lm80_groups);