hwmon: (ntc_thermistor) Avoid math overflow
The ntc thermistor code was doing math whose temporary result might
have overflowed 32-bits. We need some casts in there to make it safe.
In one example I found:
- pullup_uV: 1800000
- result of iio_read_channel_raw: 3226
- 1800000 * 3226 => 0x15a1cbc80
Signed-off-by: Doug Anderson <dianders@chromium.org>
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
diff --git a/drivers/hwmon/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c
index 8c232039..8a17f01 100644
--- a/drivers/hwmon/ntc_thermistor.c
+++ b/drivers/hwmon/ntc_thermistor.c
@@ -145,7 +145,7 @@
static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata)
{
struct iio_channel *channel = pdata->chan;
- unsigned int result;
+ s64 result;
int val, ret;
ret = iio_read_channel_raw(channel, &val);
@@ -155,10 +155,10 @@
}
/* unit: mV */
- result = pdata->pullup_uv * val;
+ result = pdata->pullup_uv * (s64) val;
result >>= 12;
- return result;
+ return (int)result;
}
static const struct of_device_id ntc_match[] = {