[SRU][N][PATCH 1/1] hwmon: (adc128d818) Fix underflows seen when writing limit attributes

[Bethany Jamison]

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

[ Upstream commit 8cad724c8537fe3e0da8004646abc00290adae40 ]

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 b0bdb43852bf7f55ba02f0cbf00b4ea7ca897bff linux-6.10.y)
CVE-2024-46759
Signed-off-by: Bethany Jamison <bethany.jamison at canonical.com>
---
 drivers/hwmon/adc128d818.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/adc128d818.c b/drivers/hwmon/adc128d818.c
index 46e3c8c507657..73fd967998472 100644
--- a/drivers/hwmon/adc128d818.c
+++ b/drivers/hwmon/adc128d818.c
@@ -176,7 +176,7 @@ static ssize_t adc128_in_store(struct device *dev,
 
 	mutex_lock(&data->update_lock);
 	/* 10 mV LSB on limit registers */
-	regval = clamp_val(DIV_ROUND_CLOSEST(val, 10), 0, 255);
+	regval = DIV_ROUND_CLOSEST(clamp_val(val, 0, 2550), 10);
 	data->in[index][nr] = regval << 4;
 	reg = index == 1 ? ADC128_REG_IN_MIN(nr) : ADC128_REG_IN_MAX(nr);
 	i2c_smbus_write_byte_data(data->client, reg, regval);
@@ -214,7 +214,7 @@ static ssize_t adc128_temp_store(struct device *dev,
 		return err;
 
 	mutex_lock(&data->update_lock);
-	regval = clamp_val(DIV_ROUND_CLOSEST(val, 1000), -128, 127);
+	regval = DIV_ROUND_CLOSEST(clamp_val(val, -128000, 127000), 1000);
 	data->temp[index] = regval << 1;
 	i2c_smbus_write_byte_data(data->client,
 				  index == 1 ? ADC128_REG_TEMP_MAX
-- 
2.34.1