linux-kernel - [PATCH 4.19 11/21] media: usbtv: Fix refcounting mixup

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Message-Id: <20201016090437.858163112@linuxfoundation.org>
Date:   Fri, 16 Oct 2020 11:07:30 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Oliver Neukum <oneukum@...e.com>,
        Ben Hutchings <ben.hutchings@...ethink.co.uk>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Subject: [PATCH 4.19 11/21] media: usbtv: Fix refcounting mixup

From: Oliver Neukum <oneukum@...e.com>

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@...e.com>
Fixes: 50e704453553 ("media: usbtv: prevent double free in error case")
CC: stable@...r.kernel.org
Reported-by: Ben Hutchings <ben.hutchings@...ethink.co.uk>
Signed-off-by: Hans Verkuil <hverkuil-cisco@...all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

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

--- 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_interf
 
 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: