[media] hdpvr: fix iteration over uninitialized lists in hdpvr_probe()

free_buff_list and rec_buff_list are initialized in the middle of hdpvr_probe(),
but if something bad happens before that, error handling code calls hdpvr_delete(),
which contains iteration over the lists (via hdpvr_free_buffers()).
The patch moves the lists initialization to the beginning and by the way fixes
goto label in error handling of registering videodev.
Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/usb/hdpvr/hdpvr-core.c

@@ -303,6 +303,11 @@ static int hdpvr_probe(struct usb_interface *interface,
 
 	dev->workqueue = 0;
 
+	/* init video transfer queues first of all */
+	/* to prevent oops in hdpvr_delete() on error paths */
+	INIT_LIST_HEAD(&dev->free_buff_list);
+	INIT_LIST_HEAD(&dev->rec_buff_list);
+
 	/* register v4l2_device early so it can be used for printks */
 	if (v4l2_device_register(&interface->dev, &dev->v4l2_dev)) {
 		dev_err(&interface->dev, "v4l2_device_register failed\n");
@@ -325,10 +330,6 @@ static int hdpvr_probe(struct usb_interface *interface,
 	if (!dev->workqueue)
 		goto error;
 
-	/* init video transfer queues */
-	INIT_LIST_HEAD(&dev->free_buff_list);
-	INIT_LIST_HEAD(&dev->rec_buff_list);
-
 	dev->options = hdpvr_default_options;
 
 	if (default_video_input < HDPVR_VIDEO_INPUTS)
@@ -405,7 +406,7 @@ static int hdpvr_probe(struct usb_interface *interface,
 				    video_nr[atomic_inc_return(&dev_nr)]);
 	if (retval < 0) {
 		v4l2_err(&dev->v4l2_dev, "registering videodev failed\n");
-		goto error;
+		goto reg_fail;
 	}
 
 	/* let the user know what node this device is now attached to */