In max16065_current_show, data->curr_sense is read twice: once for the error check and again for the calculation. Since i2c_smbus_read_byte_data returns negative error codes on failure, if the data changes to an error code between the check and the use, ADC_TO_CURR results in an incorrect calculation.
Read data->curr_sense into a local variable to ensure consistency. Note that data->curr_gain is constant and safe to access directly.
This aligns max16065_current_show with max16065_input_show, which already uses a local variable for the same reason.
Link: https://lore.kernel.org/all/CALbr=LYJ_ehtp53HXEVkSpYoub+XYSTU8Rg=o1xxMJ8=5z8... Fixes: f5bae2642e3d ("hwmon: Driver for MAX16065 System Manager and compatibles") Cc: stable@vger.kernel.org Signed-off-by: Gui-Dong Han hanguidong02@gmail.com --- Based on the discussion in the link, I will submit a series of patches to address TOCTOU issues in the hwmon subsystem by converting macros to functions or adjusting locking where appropriate. --- drivers/hwmon/max16065.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/hwmon/max16065.c b/drivers/hwmon/max16065.c index 0ccb5eb596fc..4c9e7892a73c 100644 --- a/drivers/hwmon/max16065.c +++ b/drivers/hwmon/max16065.c @@ -216,12 +216,13 @@ static ssize_t max16065_current_show(struct device *dev, struct device_attribute *da, char *buf) { struct max16065_data *data = max16065_update_device(dev); + int curr_sense = data->curr_sense;
- if (unlikely(data->curr_sense < 0)) - return data->curr_sense; + if (unlikely(curr_sense < 0)) + return curr_sense;
return sysfs_emit(buf, "%d\n", - ADC_TO_CURR(data->curr_sense, data->curr_gain)); + ADC_TO_CURR(curr_sense, data->curr_gain)); }
static ssize_t max16065_limit_store(struct device *dev,