Re: [1/1] connector/CBUS: new messaging subsystem. Revision number next.

Evgeniy Polyakov
2005-04-26T18:32:17Z

On Tue, 26 Apr 2005 13:20:08 -0500
Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote:

> On 4/26/05, Evgeniy Polyakov <johnpol@2ka.mipt.ru> wrote:
> > Yes, I found it too.
> > Following patch should be the solution:
> >
> > --- orig/drivers/connector/connector.c
> > +++ mod/drivers/connector/connector.c
> > @@ -146,13 +146,16 @@
> > spin_lock_bh(&dev->cbdev->queue_lock);
> > list_for_each_entry(__cbq, &dev->cbdev->queue_list, callback_entry) {
> > if (cn_cb_equal(&__cbq->cb->id, &msg->id)) {
> > - __cbq->cb->priv = msg;
> > +
> > + if (!test_bit(0, &work->pending)) {
> > + __cbq->cb->priv = msg;
> >
> > - __cbq->ddata = data;
> > - __cbq->destruct_data = destruct_data;
> > + __cbq->ddata = data;
> > + __cbq->destruct_data = destruct_data;
> >
>
> Still not good enough - work->pending bit gets cleared when work has
> been scheduled, but before executing payload. You still have the race.

Data pointer is copied before bit is set,
but I forget that it is not data, but another pointer
which may be overwritten.

I think we may finish it by setting skb as data,
and call kfree_skb() as destructor.

Thank you for your analysis.

> --
> Dmitry

Evgeniy Polyakov

Only failure makes us experts. -- Theo de Raadt