Re: [PATCH 1/7] Input: pegasus_notetaker: fix endpoint sanity check

Johan Hovold
2020-02-04T10:14:31Z

On Tue, Feb 04, 2020 at 10:02:32AM +0000, Greg Kroah-Hartman wrote:
> On Tue, Feb 04, 2020 at 09:24:41AM +0100, Johan Hovold wrote:
> > On Tue, Dec 10, 2019 at 12:37:31PM +0100, Johan Hovold wrote:
> > > The driver was checking the number of endpoints of the first alternate
> > > setting instead of the current one, something which could be used by a
> > > malicious device (or USB descriptor fuzzer) to trigger a NULL-pointer
> > > dereference.
> > >
> > > Fixes: 1afca2b66aac ("Input: add Pegasus Notetaker tablet driver")
> > > Cc: stable <stable@vger.kernel.org> # 4.8
> > > Cc: Martin Kepplinger <martink@posteo.de>
> > > Signed-off-by: Johan Hovold <johan@kernel.org>
> >
> > Looks like the stable tag was removed when this one was applied, and
> > similar for patches 2, 4 and 7 of this series (commits 3111491fca4f,
> > a8eeb74df5a6, 6b32391ed675 upstream).
> >
> > While the last three are mostly an issue for the syzbot fuzzer, we have
> > started backporting those as well.
> >
> > This one (bcfcb7f9b480) is more clear cut as it can be used to trigger a
> > NULL-deref.
> >
> > I only noticed because Sasha picked up one of the other patches in the
> > series which was never intended for stable.
>
> Did I end up catching all of these properly? I've had to expand my
> search for some patches like this that do not explicitly have the cc:
> stable mark on them as not all subsystems do this well (if at all.)

No, sorry, should have been more clear on that point; these four were
never picked up for stable it seems.

I was a bit surprised to see the stable-tags be removed from the
original submissions here, even if I know the net-maintainers do this
routinely, and any maintainer can of course override a submitters
judgement.

> And there's also Sasha's work in digging up patches based on patterns of
> fixes, which also is needed because of this "problem".

Yeah, seems likely that autosel would have caught these eventually.

Johan