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Date: Wed, 1 Aug 2012 15:39:32 +0200
From: Marcus Meissner <meissner@...e.de>
To: oss-security@...ts.openwall.com
Subject: Re: Re: CVE Request: NVidia Linux driver
On Wed, Aug 01, 2012 at 09:32:44AM -0400, Marc Deslauriers wrote:
> On Wed, 2012-08-01 at 15:12 +0200, Tavis Ormandy wrote:
> > Marc Deslauriers <marc.deslauriers@...onical.com>
> > wrote:
> >
> > > Hello,
> > >
> > > Could a CVE please be assigned to the following issue:
> > >
> > > The binary NVidia Linux driver allows local users to access arbitrary
> > > memory locations by leveraging GPU device-node read/write privileges, and
> > > escalate privileges to root. Possibly an incomplete fix for CVE-2012-0946.
> > >
> > > See:
> > >
> > > http://seclists.org/fulldisclosure/2012/Aug/4
> > >
> > > Thanks,
> > >
> > > Marc.
> >
> > I know that at least Gentoo does this since ~2006:
> >
> > 35 # !!! SECURITY WARNING !!!
> > 36 # DO NOT MODIFY OR REMOVE THE DEVICE FILE RELATED OPTIONS UNLESS YOU KNOW
> > 37 # WHAT YOU ARE DOING.
> > 38 # ONLY ADD TRUSTED USERS TO THE VIDEO GROUP, THESE USERS MAY BE ABLE TO
> > CRASH,
> > 39 # COMPROMISE, OR IRREPARABLY DAMAGE THE MACHINE.
> > 40 options nvidia NVreg_DeviceFileMode=432 NVreg_DeviceFileUID=0
> > NVreg_DeviceFileGID=VIDEOGID NVreg_ModifyDeviceFiles=1
> >
> >
> > http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/x11-drivers/nvidia-drivers/files/nvidia?revision=1.3&view=markup
>
>
> Well, getting rid of static groups like that is what consolekit and udev
> are for. Ideally, permissions would be granted on the device based on
> which user is at the console, as it currently done with other devices.
> Unfortunately, the design of the binary driver makes it hard to do, as
> it resets permissions itself when X loads.
>
> https://bugs.launchpad.net/ubuntu/+source/nvidia-graphics-drivers/+bug/979307
The NVIDIA is explicitly not allowed to use the udev device structure,
as udev device handling requires GPL interfaces and can only be called
from GPL drivers.
Thats why it is strange this way.
And yes, the exploit turns "I have a bad feeling about this" about this device
definitely into "this is bad".
Ciao, Marcus
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