Patch "media: usbtv: prevent double free in error case" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

media: usbtv: prevent double free in error case

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
media-usbtv-prevent-double-free-in-error-case.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Oliver Neukum <[email protected]>
Date: Mon, 8 Jan 2018 09:21:07 -0500
Subject: media: usbtv: prevent double free in error case

From: Oliver Neukum <[email protected]>

commit 50e7044535537b2a54c7ab798cd34c7f6d900bd2 upstream.

Quoting the original report:

It looks like there is a double-free vulnerability in Linux usbtv driver on an error path of usbtv_probe function. When audio registration fails, usbtv_video_free function ends up freeing usbtv data structure, which gets freed the second time under usbtv_video_fail label.

usbtv_audio_fail:

        usbtv_video_free(usbtv); =>

           v4l2_device_put(&usbtv->v4l2_dev);

              => v4l2_device_put

                  => kref_put

                      => v4l2_device_release

=> usbtv_release (CALLBACK)

                             => kfree(usbtv) (1st time)

usbtv_video_fail:

        usb_set_intfdata(intf, NULL);

        usb_put_dev(usbtv->udev);

        kfree(usbtv); (2nd time)

So, as we have refcounting, use it

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

@@ -112,6 +112,8 @@ static int usbtv_probe(struct usb_interf
 	return 0;
 
 usbtv_audio_fail:
+	/* we must not free at this point */
+	usb_get_dev(usbtv->udev);
 	usbtv_video_free(usbtv);
 
 usbtv_video_fail:

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/media-usbtv-prevent-double-free-in-error-case.patch