diff mbox series

[v4,1/2] hwmon: (lm90) Prevent integer underflows of temperature calculations

Message ID 20210621213153.28247-2-digetx@gmail.com (mailing list archive)
State Superseded
Headers show
Series Support temperature trips by HWMON core and LM90 driver | expand

Commit Message

Dmitry Osipenko June 21, 2021, 9:31 p.m. UTC
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@gmail.com>
---
 drivers/hwmon/lm90.c | 9 +++++++++
 1 file changed, 9 insertions(+)

Comments

Guenter Roeck June 22, 2021, 11:15 p.m. UTC | #1
On Tue, Jun 22, 2021 at 12:31:52AM +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@gmail.com>
> ---
>  drivers/hwmon/lm90.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
> index b53f17511b05..ee6b8190f08e 100644
> --- a/drivers/hwmon/lm90.c
> +++ b/drivers/hwmon/lm90.c
> @@ -1028,6 +1028,9 @@ static int lm90_set_temp11(struct lm90_data *data, int index, long val)
>  	struct reg *regp = &reg[index];
>  	int err;
>  
> +	/* prevent integer underflow */
> +	val = max(val, -128000l);
> +

This and the adjustment below can be moved into the if() statement for lm99.
There is no need to affect other chips.

>  	/* +16 degrees offset for temp2 for the LM99 */
>  	if (data->kind == lm99 && index <= 2)
>  		val -= 16000;
> @@ -1088,6 +1091,9 @@ static int lm90_set_temp8(struct lm90_data *data, int index, long val)
>  	struct i2c_client *client = data->client;
>  	int err;
>  
> +	/* prevent integer underflow */
> +	val = max(val, -128000l);
> +
>  	/* +16 degrees offset for temp2 for the LM99 */
>  	if (data->kind == lm99 && index == 3)
>  		val -= 16000;
> @@ -1130,6 +1136,9 @@ static int lm90_set_temphyst(struct lm90_data *data, long val)
>  	int temp;
>  	int err;
>  
> +	/* prevent integer underflow */
> +	val = max(val, -128000l);
> +
Please move this further below, just before val is used, to better
show the context why it is needed.

Thanks,
Guenter

>  	if (data->kind == adt7461 || data->kind == tmp451)
>  		temp = temp_from_u8_adt7461(data, data->temp8[LOCAL_CRIT]);
>  	else if (data->kind == max6646)
> -- 
> 2.30.2
>
diff mbox series

Patch

diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index b53f17511b05..ee6b8190f08e 100644
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -1028,6 +1028,9 @@  static int lm90_set_temp11(struct lm90_data *data, int index, long val)
 	struct reg *regp = &reg[index];
 	int err;
 
+	/* prevent integer underflow */
+	val = max(val, -128000l);
+
 	/* +16 degrees offset for temp2 for the LM99 */
 	if (data->kind == lm99 && index <= 2)
 		val -= 16000;
@@ -1088,6 +1091,9 @@  static int lm90_set_temp8(struct lm90_data *data, int index, long val)
 	struct i2c_client *client = data->client;
 	int err;
 
+	/* prevent integer underflow */
+	val = max(val, -128000l);
+
 	/* +16 degrees offset for temp2 for the LM99 */
 	if (data->kind == lm99 && index == 3)
 		val -= 16000;
@@ -1130,6 +1136,9 @@  static int lm90_set_temphyst(struct lm90_data *data, long val)
 	int temp;
 	int err;
 
+	/* prevent integer underflow */
+	val = max(val, -128000l);
+
 	if (data->kind == adt7461 || data->kind == tmp451)
 		temp = temp_from_u8_adt7461(data, data->temp8[LOCAL_CRIT]);
 	else if (data->kind == max6646)