Re: fanotify use after free.
From: Jan Kara
Date: Thu Jan 23 2014 - 18:55:59 EST
On Thu 23-01-14 16:07:45, Jiri Kosina wrote:
> On Thu, 23 Jan 2014, Jan Kara wrote:
> > > > > But refcounting seems like an overkill for this - there is exactly one
> > > > > fanotify_response_event structure iff it is a permission event. So
> > > > > something like the (completely untested) attached patch should fix the
> > > > > problem. But I agree it's a bit ugly so we might want something different.
> > > > > I'll try to think about something better tomorrow.
> > > >
> > > > Ok, In the meantime, Dave, can you verify whether this hacky patch
> > > > fixes your problem?
> > >
> > > I reported the same slab corruption yesterday as well here:
> > >
> > > https://lkml.org/lkml/2014/1/22/173
> > >
> > > With the patch applied, I am still seeing the slab corruption, preceeded
> > > by GPF (which is not there without the patch) in
> > > lockref_put_or_lock(&dentry->d_lockref) in dput():
> > Hmm, OK. Can you please send me your .config? I'll try to reproduce this
> > myself.
> The userspace is systemd-based.
Strange. I've installed systemd system (openSUSE 13.1) and it boots with
the latest Linus' kernel just fine (and I have at least FANOTIFY and
SLAB debugging set the same way as you). But it was only a KVM guest. I'll
try tomorrow with a physical machine I guess.
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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