[PATCH] hwmon: (nct6775-core) Fix overflows seen when writing limit attributes

[PATCH] hwmon: (nct6775-core) Fix overflows seen when writing limit attributes

[Pei Xiao]

DIV_ROUND_CLOSEST() after kstrtoul() results in an overflow if a large
number such as 18446744073709551615 is provided by the user.
Fix it by reordering clamp_val() and DIV_ROUND_CLOSEST() operations.

Signed-off-by: Pei Xiao <xiaopei01@kylinos.cn>
Fixes: c3963bc0a0cf ("hwmon: (nct6775) Split core and platform driver")
---
 drivers/hwmon/nct6775-core.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/hwmon/nct6775-core.c b/drivers/hwmon/nct6775-core.c
index 934fed3dd586..ee04795b98aa 100644
--- a/drivers/hwmon/nct6775-core.c
+++ b/drivers/hwmon/nct6775-core.c
@@ -2878,8 +2878,7 @@ store_target_temp(struct device *dev, struct device_attribute *attr,
 	if (err < 0)
 		return err;
 
-	val = clamp_val(DIV_ROUND_CLOSEST(val, 1000), 0,
-			data->target_temp_mask);
+	val = DIV_ROUND_CLOSEST(clamp_val(val, 0, data->target_temp_mask * 1000), 1000);
 
 	mutex_lock(&data->update_lock);
 	data->target_temp[nr] = val;
@@ -2959,7 +2958,7 @@ store_temp_tolerance(struct device *dev, struct device_attribute *attr,
 		return err;
 
 	/* Limit tolerance as needed */
-	val = clamp_val(DIV_ROUND_CLOSEST(val, 1000), 0, data->tolerance_mask);
+	val = DIV_ROUND_CLOSEST(clamp_val(val, 0, data->tolerance_mask * 1000), 1000);
 
 	mutex_lock(&data->update_lock);
 	data->temp_tolerance[index][nr] = val;
@@ -3085,7 +3084,7 @@ store_weight_temp(struct device *dev, struct device_attribute *attr,
 	if (err < 0)
 		return err;
 
-	val = clamp_val(DIV_ROUND_CLOSEST(val, 1000), 0, 255);
+	val = DIV_ROUND_CLOSEST(clamp_val(val, 0, 255000), 1000);
 
 	mutex_lock(&data->update_lock);
 	data->weight_temp[index][nr] = val;
-- 
2.34.1

Re: [PATCH] hwmon: (nct6775-core) Fix overflows seen when writing limit attributes

[Guenter Roeck]

On Tue, Nov 12, 2024 at 09:39:51AM +0800, Pei Xiao wrote:
> DIV_ROUND_CLOSEST() after kstrtoul() results in an overflow if a large
> number such as 18446744073709551615 is provided by the user.
> Fix it by reordering clamp_val() and DIV_ROUND_CLOSEST() operations.
> 
> Signed-off-by: Pei Xiao <xiaopei01@kylinos.cn>
> Fixes: c3963bc0a0cf ("hwmon: (nct6775) Split core and platform driver")

Applied.

Thanks,
Guenter