[3.12,27/82] hwmon: (ntc_thermistor) Avoid math overflow
diff mbox series

Message ID 20140220235020.288398493@linuxfoundation.org
State New, archived
Headers show
Series
  • 3.12.13-stable review
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Commit Message

Greg KH Feb. 20, 2014, 11:52 p.m. UTC
3.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Doug Anderson <dianders@chromium.org>

commit d3d89c468ceebbcf9423d1a3d66c5bf91f569570 upstream.

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>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/hwmon/ntc_thermistor.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)



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Patch
diff mbox series

--- a/drivers/hwmon/ntc_thermistor.c
+++ b/drivers/hwmon/ntc_thermistor.c
@@ -145,7 +145,7 @@  struct ntc_data {
 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 @@  static int ntc_adc_iio_read(struct ntc_t
 	}
 
 	/* 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[] = {