media: cpia2_usb: first wake up, then free in disconnect

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 <oneukum@suse.com>
Reported-by: syzbot+0c90fc937c84f97d0aa6@syzkaller.appspotmail.com
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/media/usb/cpia2/cpia2_usb.c b/drivers/media/usb/cpia2/cpia2_usb.c
index e9100a23583104d3f6fcdcb4f0dfa9535877704a..21e5454d260a0182a211d8b4fabfef123d028405 100644 (file)
--- a/drivers/media/usb/cpia2/cpia2_usb.c
+++ b/drivers/media/usb/cpia2/cpia2_usb.c
@@ -909,7 +909,6 @@ static void cpia2_usb_disconnect(struct usb_interface *intf)
        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");
@@ -921,6 +920,8 @@ static void cpia2_usb_disconnect(struct usb_interface *intf)
        DBG("Releasing interface\n");
        usb_driver_release_interface(&cpia2_driver, intf);
 
+       v4l2_device_put(&cam->v4l2_dev);
+
        LOG("CPiA2 camera disconnected.\n");
 }