Re: [PATCH v4 1/2] hwmon: (lm90) Prevent integer underflows of temperature calculations
From: Guenter Roeck <linux@roeck-us.net>
Date: 2021-06-22 23:15:30
Also in:
linux-hwmon, linux-tegra, lkml
On Tue, Jun 22, 2021 at 12:31:52AM +0300, Dmitry Osipenko wrote:
quoted hunk ↗ jump to hunk
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 = ®[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.
quoted hunk ↗ jump to hunk
/* +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