[SRU][N][PATCH 1/1] hwmon: (lm95234) Fix underflows seen when writing limit attributes

[Bethany Jamison]

From: Guenter Roeck <linux at 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 at roeck-us.net>
Signed-off-by: Sasha Levin <sashal at kernel.org>
(cherry picked from commit 16f42953231be1e7be77bc24005270d9e0d9d2ee linux-6.10.y)
CVE-2024-46758
Signed-off-by: Bethany Jamison <bethany.jamison at canonical.com>
---
 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 67b9d7636ee42..37e8e9679aeb6 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;
-- 
2.34.1