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From:   Roderick Colenbrander <thunderbird2k@gmail.com>
Date:   Fri, 4 Jan 2019 08:38:28 -0800
Message-ID: <CAEc3jaAf2Cd_1vS8Xo-VoJzJKxWJDNm++=eY+5G2dHa5Jo2gXg@mail.gmail.com>
Subject: Re: NULL pointer dereference when writing fuzzed data to /dev/uhid
To:     Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc:     Anatoly Trosinenko <anatoly.trosinenko@gmail.com>,
        Jiri Kosina <jikos@kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
        "open list:HID CORE LAYER" <linux-input@vger.kernel.org>
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> > For sony.bin:
> >
> > root@kvm-xfstests:~# cat /vtmp/sony.bin > /dev/uhid
> > [   16.891931] sony 0003:054C:1000.0001: unknown main item tag 0x0
> > [   16.892432] sony 0003:054C:1000.0001: unknown main item tag 0x0
> > [   16.892894] sony 0003:054C:1000.0001: unknown main item tag 0x0
> > [   16.893362] sony 0003:054C:1000.0001: unknown main item tag 0x0
> > [   16.893844] sony 0003:054C:1000.0001: unknown main item tag 0x0
> > [   16.895389] sony 0003:054C:1000.0001: unknown main item tag 0x0
> > [   16.898165] sony 0003:054C:1000.0001: ignoring exceeding usage max
> > [   16.901190] sony 0003:054C:1000.0001: unknown main item tag 0x0
> > [   16.903797] sony 0003:054C:1000.0001: unknown main item tag 0x0
> > [   16.906401] sony 0003:054C:1000.0001: unknown main item tag 0x0
> > [   16.908957] sony 0003:054C:1000.0001: unknown main item tag 0x0
> > [   16.911449] sony 0003:054C:1000.0001: unknown main item tag 0x0
> > [   16.913936] sony 0003:054C:1000.0001: unknown main item tag 0x1
> > [   16.916551] sony 0003:054C:1000.0001: unknown main item tag 0x0
> > [   16.918454] sony 0003:054C:1000.0001: unknown main item tag 0x0
> > [   16.919743] sony 0003:054C:1000.0001: unknown main item tag 0x4
> > [   16.920834] sony 0003:054C:1000.0001: unknown main item tag 0xe
> > [   16.921904] sony 0003:054C:1000.0001: unknown main item tag 0xe
> > [   16.923006] sony 0003:054C:1000.0001: unknown main item tag 0x0
> > [   16.924082] sony 0003:054C:1000.0001: unknown main item tag 0x2
> > [   16.925195] sony 0003:054C:1000.0001: unknown main item tag 0x0
> > [   16.926289] sony 0003:054C:1000.0001: unknown main item tag 0x0
> > [   16.927400] sony 0003:054C:1000.0001: unknown main item tag 0x0
> > [   16.928546] BUG: unable to handle kernel NULL pointer dereference
> > at 0000000000000028
> > [   16.929951] #PF error: [normal kernel read fault]
> > [   16.930884] PGD 800000007a52b067 P4D 800000007a52b067 PUD 0
> > [   16.931836] Oops: 0000 [#1] SMP PTI
> > [   16.932437] CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted
> > 4.20.0-xfstests-10979-g96d4f267e40 #1
> > [   16.933752] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
> > BIOS 1.11.1-1ubuntu1 04/01/2014
> > [   16.935372] Workqueue: events uhid_device_add_worker
> > [   16.936321] RIP: 0010:hid_validate_values+0x48/0x110
>
> In a sense, it's good to have a fault there because this was added to
> make sure we do not blindly accept any data. The fact that it doesn't
> fail gracefully is a sign that there is something else.
> Maybe Roderick could have a look?
>
> Cheers,
> Benjamin
>

Sure I can have a look. Would you be able to share the sony.bin file?
Did you inject a particular device? We do a lot of remapping and
processing in hid-sony at startup. It is probably related to that.

Thanks,
Roderick