Re: [PATCH v1] s390/vfio-ap: Signal eventfd when guest AP configuration is changed

[Anthony Krowiak]

On 1/16/25 2:18 PM, Halil Pasic wrote:
> On Thu, 16 Jan 2025 11:52:28 -0500
> Alex Williamson <alex.williamson@xxxxxxxxxx> wrote:
>
> > > > Alex, does the above answer your question on what guards against UAF (the
> > > > short answer is: matrix_dev->mdevs_lock)?
> > Yes, that answers my question, thanks for untangling it.  We might
> > consider a lockdep_assert_held() in the new
> > signal_guest_ap_cfg_changed() since it does get called from a variety
> > of paths and we need that lock to prevent the UAF.
> Yes I second that! I was thinking about it myself yesterday. And there
> are also a couple of other functions that expect to be called with
> certain locks held. I would love to see lockdep_assert_held() there
> as well.
>
> Since I went through that code last night I could spin a patch that
> catches some of these at least. But if I don't within two weeks, I
> won't be grumpy if somebody else picks that up.

Sure, sounds like a good idea. Don't worry about it, I can take care of 
it. Thanks.

> Regards,
> Halil