Re: [PATCH] 9p/xen: drain response work after unbinding IRQ

[Dominique Martinet <asmadeus@codewreck.org>]

Juergen Gross wrote on Thu, Oct 08, 2026 at 12:42:21PM +0200:
> > This one makes sense to me and I've picked it up, but I think
> > "9p/xen: fix use-after-free in p9_xen_request"[1] adding a refcount to
> > the front_priv is too much complexity vs. my understanding of the
> > current threat model -- I can pick it up if someome who understands xen
> > better than me has a proper look.
> > 
> > Stefano or Jürgen if you care / have time?
> > 
> > [1] https://lore.kernel.org/r/20260529103416.81378-1-zhaoyz24@mails.tsinghua.edu.cn
> 
> I think [1] should be taken.
> 
> We try to harden frontends against potentially malicious backends running
> in a driver domain. Such a backend could cause the device to be removed on
> the frontend side, so the attack vector is present.
> 
> The only reason this doesn't qualify as a Xen security issue is that the
> 9pfs frontend hasn't been yet declared to be security supported regarding
> attacks by the backend. Hopefully we will get there.

As said above I'm happy to take it under the condition that someone who
can validate the patch has a proper look; I don't have much time for 9p
right now and my setup doesn't include any test for xen so I'd rather be
cautious

Thanks,
-- 
Dominique Martinet | Asmadeus