[PATCH 5.15 054/128] hwmon: (lm90) Prevent integer overflow/underflow in hysteresis calculations

Greg Kroah-Hartman
2021-12-27T15:52:57Z

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

[ Upstream commit 55840b9eae5367b5d5b29619dc2fb7e4596dba46 ]

Commit b50aa49638c7 ("hwmon: (lm90) Prevent integer underflows of
temperature calculations") addressed a number of underflow situations
when writing temperature limits. However, it missed one situation, seen
when an attempt is made to set the hysteresis value to MAX_LONG and the
critical temperature limit is negative.

Use clamp_val() when setting the hysteresis temperature to ensure that
the provided value can never overflow or underflow.

Fixes: b50aa49638c7 ("hwmon: (lm90) Prevent integer underflows of temperature calculations")
Cc: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/hwmon/lm90.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index d40e3bb801d07..f6e6c7c6c73f8 100644
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -1143,8 +1143,8 @@ static int lm90_set_temphyst(struct lm90_data *data, long val)
else
temp = temp_from_s8(data->temp8[LOCAL_CRIT]);

- /* prevent integer underflow */
- val = max(val, -128000l);
+ /* prevent integer overflow/underflow */
+ val = clamp_val(val, -128000l, 255000l);

data->temp_hyst = hyst_to_reg(temp - val);
err = i2c_smbus_write_byte_data(client, LM90_REG_W_TCRIT_HYST,
--
2.34.1