hwmon: (max16065) Use local variable to avoid TOCTOU

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=[e-mail]/
Fixes: f5bae2642e3d ("hwmon: Driver for MAX16065 System Manager and compatibles")
Cc: [e-mail]
Signed-off-by: Gui-Dong Han <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Guenter Roeck <[e-mail]>

drivers/hwmon/max16065.c

···
 				     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,