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: Yavuz, Tuba tuba@ece.ufl.edu Signed-off-by: Oliver Neukum oneukum@suse.com CC: stable@vger.kernel.org --- drivers/media/usb/usbtv/usbtv-core.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/drivers/media/usb/usbtv/usbtv-core.c b/drivers/media/usb/usbtv/usbtv-core.c index 127f8a0c098b..0c2e628e8723 100644 --- a/drivers/media/usb/usbtv/usbtv-core.c +++ b/drivers/media/usb/usbtv/usbtv-core.c @@ -112,6 +112,8 @@ static int usbtv_probe(struct usb_interface *intf, return 0;

usbtv_audio_fail: + /* we must not free at this point */ + usb_get_dev(usbtv->udev); usbtv_video_free(usbtv);

usbtv_video_fail: