| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.16 047/125] hwmon: (lm92) Prevent overflow problem when writing large limits | Date | Wed, 3 Sep 2014 15:06:44 -0700 |
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3.16-stable review patch. If anyone has any objections, please let me know.
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From: Axel Lin <axel.lin@ingics.com>
commit 5b963089161b8fb244889c972edf553b9d737545 upstream.
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] Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/hwmon/lm92.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-)
--- a/drivers/hwmon/lm92.c +++ b/drivers/hwmon/lm92.c @@ -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 devi 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; }
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