Commit 50e70445 authored by Oliver Neukum's avatar Oliver Neukum Committed by Mauro Carvalho Chehab

media: usbtv: prevent double free in error case

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
Reported-by: default avatarYavuz, Tuba <tuba@ece.ufl.edu>
Signed-off-by: default avatarOliver Neukum <oneukum@suse.com>
CC: stable@vger.kernel.org
Signed-off-by: default avatarHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
parent 81b9de43
...@@ -112,6 +112,8 @@ static int usbtv_probe(struct usb_interface *intf, ...@@ -112,6 +112,8 @@ static int usbtv_probe(struct usb_interface *intf,
return 0; return 0;
usbtv_audio_fail: usbtv_audio_fail:
/* we must not free at this point */
usb_get_dev(usbtv->udev);
usbtv_video_free(usbtv); usbtv_video_free(usbtv);
usbtv_video_fail: usbtv_video_fail:
......
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