HID: hid-ntrig: Prevent memory leak in ntrig_report_version()

Use a scope-based cleanup helper for the buffer allocated with kmalloc()
in ntrig_report_version() to simplify the cleanup logic and prevent
memory leaks (specifically the !hid_is_usb()-case one).

[jkosina@suse.com: elaborate on the actual existing leak]
Fixes: 185c926 ("HID: hid-ntrig: fix unable to handle page fault in ntrig_report_version()")
Signed-off-by: Masami Ichikawa <masami256@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

Author: masami256

drivers/hid/hid-ntrig.c

@@ -142,13 +142,13 @@ static void ntrig_report_version(struct hid_device *hdev)
 	int ret;
 	char buf[20];
 	struct usb_device *usb_dev = hid_to_usb_dev(hdev);
-	unsigned char *data = kmalloc(8, GFP_KERNEL);
+	unsigned char *data __free(kfree) = kmalloc(8, GFP_KERNEL);
 
 	if (!hid_is_usb(hdev))
 		return;
 
 	if (!data)
-		goto err_free;
+		return;
 
 	ret = usb_control_msg(usb_dev, usb_rcvctrlpipe(usb_dev, 0),
 			      USB_REQ_CLEAR_FEATURE,
@@ -163,9 +163,6 @@ static void ntrig_report_version(struct hid_device *hdev)
 		hid_info(hdev, "Firmware version: %s (%02x%02x %02x%02x)\n",
 			 buf, data[2], data[3], data[4], data[5]);
 	}
-
-err_free:
-	kfree(data);
 }
 
 static ssize_t show_phys_width(struct device *dev,