diff options
| author | Gui-Dong Han <hanguidong02@gmail.com> | 2025-11-25 00:55:08 +0800 |
|---|---|---|
| committer | Guenter Roeck <linux@roeck-us.net> | 2025-11-24 11:45:16 -0800 |
| commit | 4faaa77d6b32347ea6af74d5fd2f34c3922aeee6 (patch) | |
| tree | 8e6531d3ab615b82f07eed6405b21f3960237023 | |
| parent | edbce49ea6535a56aac3a5e211cf7af873d7221d (diff) | |
hwmon: (emc2103) Add locking to avoid TOCTOU
The functions fan1_input_show and fan1_target_show check shared data for
zero before using it as a divisor. These accesses are currently
lockless. If the data changes to zero between the check and the
division, it causes a divide-by-zero error.
Explicitly acquire the update lock around these checks and calculations
to ensure the data remains stable, preventing Time-of-Check to
Time-of-Use (TOCTOU) race conditions.
Link: https://lore.kernel.org/all/CALbr=LYJ_ehtp53HXEVkSpYoub+XYSTU8Rg=o1xxMJ8=5z8B-g@mail.gmail.com/
Signed-off-by: Gui-Dong Han <hanguidong02@gmail.com>
Link: https://lore.kernel.org/r/20251124165508.4667-1-hanguidong02@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
| -rw-r--r-- | drivers/hwmon/emc2103.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/hwmon/emc2103.c b/drivers/hwmon/emc2103.c index 60eddc7b0270..9b8e925af030 100644 --- a/drivers/hwmon/emc2103.c +++ b/drivers/hwmon/emc2103.c @@ -277,8 +277,10 @@ fan1_input_show(struct device *dev, struct device_attribute *da, char *buf) { struct emc2103_data *data = emc2103_update_device(dev); int rpm = 0; + mutex_lock(&data->update_lock); if (data->fan_tach != 0) rpm = (FAN_RPM_FACTOR * data->fan_multiplier) / data->fan_tach; + mutex_unlock(&data->update_lock); return sprintf(buf, "%d\n", rpm); } @@ -363,10 +365,12 @@ fan1_target_show(struct device *dev, struct device_attribute *da, char *buf) struct emc2103_data *data = emc2103_update_device(dev); int rpm = 0; + mutex_lock(&data->update_lock); /* high byte of 0xff indicates disabled so return 0 */ if ((data->fan_target != 0) && ((data->fan_target & 0x1fe0) != 0x1fe0)) rpm = (FAN_RPM_FACTOR * data->fan_multiplier) / data->fan_target; + mutex_unlock(&data->update_lock); return sprintf(buf, "%d\n", rpm); } |