[PATCH 4.19 13/32] media: cpia2_usb: first wake up, then free in disconnect

[Greg Kroah-Hartman]

From: Oliver Neukum <oneu...@suse.com>

commit eff73de2b1600ad8230692f00bc0ab49b166512a upstream.

Kasan reported a use after free in cpia2_usb_disconnect()
It first freed everything and then woke up those waiting.
The reverse order is correct.

Fixes: 6c493f8b28c67 ("[media] cpia2: major overhaul to get it in a working 
state again")

Signed-off-by: Oliver Neukum <oneu...@suse.com>
Reported-by: syzbot+0c90fc937c84f97d0...@syzkaller.appspotmail.com
Signed-off-by: Hans Verkuil <hverkuil-ci...@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+sams...@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/media/usb/cpia2/cpia2_usb.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/media/usb/cpia2/cpia2_usb.c
+++ b/drivers/media/usb/cpia2/cpia2_usb.c
@@ -902,7 +902,6 @@ static void cpia2_usb_disconnect(struct
        cpia2_unregister_camera(cam);
        v4l2_device_disconnect(&cam->v4l2_dev);
        mutex_unlock(&cam->v4l2_lock);
-       v4l2_device_put(&cam->v4l2_dev);
 
        if(cam->buffers) {
                DBG("Wakeup waiting processes\n");
@@ -911,6 +910,8 @@ static void cpia2_usb_disconnect(struct
                wake_up_interruptible(&cam->wq_stream);
        }
 
+       v4l2_device_put(&cam->v4l2_dev);
+
        LOG("CPiA2 camera disconnected.\n");
 }