[PATCH AUTOSEL 6.1 56/61] hwmon: (lm95234) Fix underflows seen when writing limit attributes

Sasha Levin
2024-08-01T00:31:24Z

From: Guenter Roeck <linux@roeck-us.net>

[ Upstream commit af64e3e1537896337405f880c1e9ac1f8c0c6198 ]

DIV_ROUND_CLOSEST() after kstrtol() results in an underflow if a large
negative number such as -9223372036854775808 is provided by the user.
Fix it by reordering clamp_val() and DIV_ROUND_CLOSEST() operations.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/hwmon/lm95234.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/hwmon/lm95234.c b/drivers/hwmon/lm95234.c
index b4a9d0c223c4a..db570fe84132c 100644
--- a/drivers/hwmon/lm95234.c
+++ b/drivers/hwmon/lm95234.c
@@ -301,7 +301,8 @@ static ssize_t tcrit2_store(struct device *dev, struct device_attribute *attr,
if (ret < 0)
return ret;

- val = clamp_val(DIV_ROUND_CLOSEST(val, 1000), 0, index ? 255 : 127);
+ val = DIV_ROUND_CLOSEST(clamp_val(val, 0, (index ? 255 : 127) * 1000),
+ 1000);

mutex_lock(&data->update_lock);
data->tcrit2[index] = val;
@@ -350,7 +351,7 @@ static ssize_t tcrit1_store(struct device *dev, struct device_attribute *attr,
if (ret < 0)
return ret;

- 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->tcrit1[index] = val;
@@ -391,7 +392,7 @@ static ssize_t tcrit1_hyst_store(struct device *dev,
if (ret < 0)
return ret;

- val = DIV_ROUND_CLOSEST(val, 1000);
+ val = DIV_ROUND_CLOSEST(clamp_val(val, -255000, 255000), 1000);
val = clamp_val((int)data->tcrit1[index] - val, 0, 31);

mutex_lock(&data->update_lock);
@@ -431,7 +432,7 @@ static ssize_t offset_store(struct device *dev, struct device_attribute *attr,
return ret;

/* Accuracy is 1/2 degrees C */
- val = clamp_val(DIV_ROUND_CLOSEST(val, 500), -128, 127);
+ val = DIV_ROUND_CLOSEST(clamp_val(val, -64000, 63500), 500);

mutex_lock(&data->update_lock);
data->toffset[index] = val;
--
2.43.0