Re: [PATCH v5 1/2] hwmon: (lm90) Prevent integer underflows of temperature calculations

From: Guenter Roeck
Date: Thu Jun 24 2021 - 10:14:57 EST


On Wed, Jun 23, 2021 at 07:22:30AM +0300, Dmitry Osipenko wrote:
> The min/max/crit and all other temperature values that are passed to
> the driver are unlimited and value that is close to INT_MIN results in
> integer underflow of the temperature calculations made by the driver
> for LM99 sensor. Temperature hysteresis is among those values that need
> to be limited, but limiting of hysteresis is independent from the sensor
> version. Add the missing limits.
>
> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>

Applied.

Thanks,
Guenter

> ---
> drivers/hwmon/lm90.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
> index b53f17511b05..567b7c521f38 100644
> --- a/drivers/hwmon/lm90.c
> +++ b/drivers/hwmon/lm90.c
> @@ -1029,8 +1029,11 @@ static int lm90_set_temp11(struct lm90_data *data, int index, long val)
> int err;
>
> /* +16 degrees offset for temp2 for the LM99 */
> - if (data->kind == lm99 && index <= 2)
> + if (data->kind == lm99 && index <= 2) {
> + /* prevent integer underflow */
> + val = max(val, -128000l);
> val -= 16000;
> + }
>
> if (data->kind == adt7461 || data->kind == tmp451)
> data->temp11[index] = temp_to_u16_adt7461(data, val);
> @@ -1089,8 +1092,11 @@ static int lm90_set_temp8(struct lm90_data *data, int index, long val)
> int err;
>
> /* +16 degrees offset for temp2 for the LM99 */
> - if (data->kind == lm99 && index == 3)
> + if (data->kind == lm99 && index == 3) {
> + /* prevent integer underflow */
> + val = max(val, -128000l);
> val -= 16000;
> + }
>
> if (data->kind == adt7461 || data->kind == tmp451)
> data->temp8[index] = temp_to_u8_adt7461(data, val);
> @@ -1137,6 +1143,9 @@ 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);
> +
> data->temp_hyst = hyst_to_reg(temp - val);
> err = i2c_smbus_write_byte_data(client, LM90_REG_W_TCRIT_HYST,
> data->temp_hyst);