Using DIV_ROUND_CLOSEST() on an unbound value can result in underflows.
Indeed, module test scripts report:
temp1_max: Suspected underflow: [min=0, read 255000, written -9223372036854775808]
temp1_crit: Suspected underflow: [min=0, read 255000, written -9223372036854775808]
Fix by introducing an extra set of clamping.
Fixes: 5372d2d71c46 ("hwmon: Driver for Maxim MAX6697 and compatibles")
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
drivers/hwmon/max6697.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/hwmon/max6697.c b/drivers/hwmon/max6697.c
index 1111b2ea55ee..20981f9443dd 100644
--- a/drivers/hwmon/max6697.c
+++ b/drivers/hwmon/max6697.c
@@ -311,6 +311,7 @@ static ssize_t temp_store(struct device *dev,
return ret;
mutex_lock(&data->update_lock);
+ temp = clamp_val(temp, -1000000, 1000000); /* prevent underflow */
temp = DIV_ROUND_CLOSEST(temp, 1000) + data->temp_offset;
temp = clamp_val(temp, 0, data->type == max6581 ? 255 : 127);
data->temp[nr][index] = temp;
--
2.39.2
