[PATCH] hwmon: lm80: fix a missing check of return value

* [PATCH] hwmon: lm80: fix a missing check of return value
@ 2018-12-21  6:13 Kangjie Lu
  2018-12-21 14:43 ` Guenter Roeck
  2019-01-02 15:23 ` Dan Carpenter
  0 siblings, 2 replies; 4+ messages in thread
From: Kangjie Lu @ 2018-12-21  6:13 UTC (permalink / raw)
  To: kjlu; +Cc: pakki001, Jean Delvare, Guenter Roeck, linux-hwmon, linux-kernel

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>
---
 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..fca6363cd77f 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 ret;
+
+	ret = kstrtoul(buf, 10, &val);
+	if (ret < 0)
+		return ret;
 
 	/* 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)));
+	ret = lm80_read_value(client, LM80_REG_FANDIV);
+	if (ret < 0)
+		return ret;
+	reg = (ret & ~(3 << (2 * (nr + 1))))
+	      | (data->fan_div[nr] << (2 * (nr + 1)));
 	lm80_write_value(client, LM80_REG_FANDIV, reg);
 
 	/* Restore fan_min */
-- 
2.17.2 (Apple Git-113)

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