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Date: Thu, 21 Sep 2017 10:37:39 +0200
From: Johan Hovold <johan@kernel.org>
To: Andrey Konovalov <andreyknvl@google.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>,
        Oleh Kravchenko <oleg@kaa.org.ua>,
        Hans Verkuil <hans.verkuil@cisco.com>, Johan Hovold <johan@kernel.org>,
        linux-media@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        Dmitry Vyukov <dvyukov@google.com>, Kostya Serebryany <kcc@google.com>,
        syzkaller <syzkaller@googlegroups.com>
Subject: Re: usb/media/cx231xx: null-ptr-deref in cx231xx_usb_probe
Message-ID: <20170921083739.GI3198@localhost>
References: <CAAeHK+zQm2DJT-1POrnB+1OFGVdTCOg+rpZODW=UPyLM1Ysr=g@mail.gmail.com>
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On Wed, Sep 20, 2017 at 08:54:08PM +0200, Andrey Konovalov wrote:
> Hi!
> 
> I've got the following report while fuzzing the kernel with syzkaller.
> 
> On commit ebb2c2437d8008d46796902ff390653822af6cc4 (Sep 18).
> 
> The null-ptr-deref happens on assoc_desc->bFirstInterface, where
> assoc_desc = udev->actconfig->intf_assoc[0]. There seems to be no
> check that the device actually contains an Interface Association
> Descriptor.

That is indeed a bug; I'll respond to this mail with a fix.

Thanks,
Johan