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hwmon: (lm92) Prevent overflow problem when writing large limits 

On platforms with sizeof(int) < sizeof(long), writing a temperature
limit larger than MAXINT will result in unpredictable limit values
written to the chip. Avoid auto-conversion from long to int to fix
the problem.

The hysteresis temperature range depends on the value of
data->temp[attr->index], since val is subtracted from it.
Use a wider clamp, [-120000, 220000] should do to cover the
possible range. Also add missing TEMP_TO_REG() on writes into
cached hysteresis value.

Also uses clamp_val to simplify the code a bit.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
[Guenter Roeck: Fixed double TEMP_TO_REG on hysteresis updates]
Cc: stable@vger.kernel.org
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Axel Lin 2014-08-05 10:08:31 +08:00 committed by Guenter Roeck
parent f4d33337ea
commit 5b96308916
1 changed files with 6 additions and 7 deletions
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13
drivers/hwmon/lm92.c
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@ -74,12 +74,9 @@ static inline int TEMP_FROM_REG(s16 reg)
return reg / 8 * 625 / 10;
}
static inline s16 TEMP_TO_REG(int val)
static inline s16 TEMP_TO_REG(long val)
{
if (val <= -60000)
return -60000 * 10 / 625 * 8;
if (val >= 160000)
return 160000 * 10 / 625 * 8;
val = clamp_val(val, -60000, 160000);
return val * 10 / 625 * 8;
}
@ -206,10 +203,12 @@ static ssize_t set_temp_hyst(struct device *dev,
if (err)
return err;
val = clamp_val(val, -120000, 220000);
mutex_lock(&data->update_lock);
data->temp[t_hyst] = TEMP_FROM_REG(data->temp[attr->index]) - val;
data->temp[t_hyst] =
TEMP_TO_REG(TEMP_FROM_REG(data->temp[attr->index]) - val);
i2c_smbus_write_word_swapped(client, LM92_REG_TEMP_HYST,
TEMP_TO_REG(data->temp[t_hyst]));
data->temp[t_hyst]);
mutex_unlock(&data->update_lock);
return count;
}