[3.11.y.z extended stable] Patch "hwmon: (ntc_thermistor) Avoid math overflow" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    hwmon: (ntc_thermistor) Avoid math overflow

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From ecc7003f03b801fa7c7489936c2151783a67c594 Mon Sep 17 00:00:00 2001
From: Doug Anderson <dianders at chromium.org>
Date: Thu, 13 Feb 2014 14:39:34 -0800
Subject: hwmon: (ntc_thermistor) Avoid math overflow

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 at chromium.org>
Signed-off-by: Guenter Roeck <linux at roeck-us.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/hwmon/ntc_thermistor.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c
index 830a842..4a80a54 100644
--- 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_thermistor_platform_data *pdata)
 	}

 	/* 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[] = {
--
1.9.0