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Date:   Tue, 4 Feb 2020 11:14:35 +0100
From:   Johan Hovold <johan@kernel.org>
To:     Greg KH <gregkh@linuxfoundation.org>
Cc:     Johan Hovold <johan@kernel.org>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        stable@vger.kernel.org, linux-input@vger.kernel.org,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        Martin Kepplinger <martink@posteo.de>
Subject: Re: [PATCH 1/7] Input: pegasus_notetaker: fix endpoint sanity check
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References: <20191210113737.4016-1-johan@kernel.org>
 <20191210113737.4016-2-johan@kernel.org>
 <20200204082441.GD26725@localhost>
 <20200204100232.GB1088789@kroah.com>
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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