[tip: perf/urgent] media: usbtv: Fix refcounting mixup

[tip-bot2 for Oliver Neukum]

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     1eaed405fcd22e52a438b619e6ea85539f1c150a
Gitweb:        https://git.kernel.org/tip/1eaed405fcd22e52a438b619e6ea85539f1c150a
Author:        Oliver Neukum <oneukum@xxxxxxxx>
AuthorDate:    Thu, 24 Sep 2020 11:14:10 +02:00
Committer:     Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
CommitterDate: Sat, 17 Oct 2020 08:31:21 +02:00

media: usbtv: Fix refcounting mixup

commit bf65f8aabdb37bc1a785884374e919477fe13e10 upstream.

The premature free in the error path is blocked by V4L
refcounting, not USB refcounting. Thanks to
Ben Hutchings for review.

[v2] corrected attributions

Signed-off-by: Oliver Neukum <oneukum@xxxxxxxx>
Fixes: 50e704453553 ("media: usbtv: prevent double free in error case")
CC: stable@xxxxxxxxxxxxxxx
Reported-by: Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/media/usb/usbtv/usbtv-core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/usbtv/usbtv-core.c b/drivers/media/usb/usbtv/usbtv-core.c
index ee9c656..2308c0b 100644
--- a/drivers/media/usb/usbtv/usbtv-core.c
+++ b/drivers/media/usb/usbtv/usbtv-core.c
@@ -113,7 +113,8 @@ static int usbtv_probe(struct usb_interface *intf,
 
 usbtv_audio_fail:
 	/* we must not free at this point */
-	usb_get_dev(usbtv->udev);
+	v4l2_device_get(&usbtv->v4l2_dev);
+	/* this will undo the v4l2_device_get() */
 	usbtv_video_free(usbtv);
 
 usbtv_video_fail: