hwmon: (max16065) Use local variable to avoid TOCTOU

[ Upstream commit b8d5acdcf525f44e521ca4ef51dce4dac403dab4 ]

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=5z8B-g@mail.gmail.com/
Fixes: f5bae2642e3d ("hwmon: Driver for MAX16065 System Manager and compatibles")
Cc: stable@vger.kernel.org
Signed-off-by: Gui-Dong Han <hanguidong02@gmail.com>
Link: https://lore.kernel.org/r/20251128124709.3876-1-hanguidong02@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hwmon/max16065.c b/drivers/hwmon/max16065.c
index 66d92f705136e16903e7ff165d3fdec8a5b30fb0..5787db933fad601aaf6c527d7db9dd9835ef37e8 100644 (file)
--- 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,