Syzkaller has reported a general protection fault at function ir_raw_event_store_with_filter(). This crash is caused by a NULL pointer dereference of dev->raw pointer, even though it is checked for NULL in the same function, which means there is a race condition. It occurs due to the incorrect order of actions in the streamzap_disconnect() function: rc_unregister_device() is called before usb_kill_urb(). The dev->raw pointer is freed and set to NULL in rc_unregister_device(), and only after that usb_kill_urb() waits for in-progress requests to finish.
If rc_unregister_device() is called while streamzap_callback() handler is not finished, this can lead to accessing freed resources. Thus rc_unregister_device() should be called after usb_kill_urb().
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Fixes: 8e9e60640067 ("V4L/DVB: staging/lirc: port lirc_streamzap to ir-core") Cc: stable@vger.kernel.org Reported-by: syzbot+34008406ee9a31b13c73@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=34008406ee9a31b13c73 Signed-off-by: Murad Masimov m.masimov@mt-integration.ru --- drivers/media/rc/streamzap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/media/rc/streamzap.c b/drivers/media/rc/streamzap.c index 9b209e687f25..2ce62fe5d60f 100644 --- a/drivers/media/rc/streamzap.c +++ b/drivers/media/rc/streamzap.c @@ -385,8 +385,8 @@ static void streamzap_disconnect(struct usb_interface *interface) if (!sz) return;
- rc_unregister_device(sz->rdev); usb_kill_urb(sz->urb_in); + rc_unregister_device(sz->rdev); usb_free_urb(sz->urb_in); usb_free_coherent(usbdev, sz->buf_in_len, sz->buf_in, sz->dma_in);
-- 2.39.2