From: =?utf-8?Q?Bj=C3=B8rn_Mork?= <bjorn@mork.no>
To: Sasha Levin <sasha.levin@oracle.com>
Cc: Jiri Slaby <jslaby@suse.cz>, LKML <linux-kernel@vger.kernel.org>,
        stable <stable@vger.kernel.org>, lwn@lwn.net
Subject: Re: stable-security kernel updates
Organization: m
References: <5717DD8A.4000707@oracle.com> <571876AB.2060106@suse.cz>
	<5718B57D.4000504@oracle.com>
Date: Thu, 21 Apr 2016 14:26:42 +0200
In-Reply-To: <5718B57D.4000504@oracle.com> (Sasha Levin's message of "Thu, 21
	Apr 2016 07:11:57 -0400")
Message-ID: <87twiv2lml.fsf@nemi.mork.no>
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Sasha Levin <sasha.levin@oracle.com> writes:
> On 04/21/2016 02:43 AM, Jiri Slaby wrote:
>
>> Input: powermate - fix oops with malicious USB descriptors
>
> This requires physical access to the machine.

You wish.

Say you have some internal USB connected device with replacable
firmware.  LTE modem, fingerprint reader, webcam - you name it. How do
you know that this cannot be abused to impersonate some other USB
device?  Yes, changing the firmware of those devices should of course
require admin privileges.  But is that always so?  Writing firmware to a
modem, for example, is typically done over a serial device similar to
the one used for normal modem operations. Privileges necessary to manage
the modem will also include changing the firmware. Physical access is
not necessary.

Do you trust the firmware protection of all your non-removable USB
devices?


Bjørn