Re: [PATCH] usb: misc: fix improper handling of refcount in uss720_probe()

[Hangyu Hua]

Oh, i sorry. Thank you for your reminder. I will remake a patch carefully.

On 2022/4/6 19:47, Oliver Neukum wrote:
> On 06.04.22 09:33, Hangyu Hua wrote:
> > usb_put_dev shouldn't be called when uss720_probe succeeds because of
> > priv->usbdev. At the same time, priv->usbdev shouldn't be set to NULL
> > before destroy_priv in uss720_disconnect because usb_put_dev is in
> > destroy_priv.
>
> Hi,
>
> I am sorry, but that's a clear NACK.
> > @@ -754,13 +753,13 @@ static void uss720_disconnect(struct usb_interface *intf)
> >   	usb_set_intfdata(intf, NULL);
> >   	if (pp) {
> >   		priv = pp->private_data;
> > -		priv->usbdev = NULL;
> >   		priv->pp = NULL;
> >   		dev_dbg(&intf->dev, "parport_remove_port\n");
> >   		parport_remove_port(pp);
> >   		parport_put_port(pp);
> >   		kill_all_async_requests_priv(priv);
> >   		kref_put(&priv->ref_count, destroy_priv);
> > +		priv->usbdev = NULL;
>
> That is a clear use after free The patch is no good in this state..
>
>      HTH
>          Oliver