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Date: Thu, 21 Jan 2010 10:46:00 +0100
From: Ludwig Nussel <ludwig.nussel@...e.de>
To: oss-security@...ts.openwall.com,
	Jerome Glisse <jglisse@...hat.com>
Subject: Re: CVE request - kernel: drm/radeon: r6xx/r7xx
 possible security issue, system ram access

Eugene Teo wrote:
> On 01/21/2010 04:44 PM, Eugene Teo wrote:
> > Quoting from the patch description:
> > "This patch workaround a possible security issue which can allow user to
> > abuse drm on r6xx/r7xx hw to access any system ram memory. This patch
> > doesn't break userspace, it detect "valid" old use of CB_COLOR[0-7]_FRAG
> [...]
> > The attack is theoretical. To exploit this you need access to the drm
> > device file which is usually set to 666 to allow users to have 3D
> > acceleration.
> 
> Sorry, correction, you need to be root to open the drm device file. 

You lost me. Do you mean the driver itself checks for CAP_SYS_ADMIN for this
particular operation? It wouldn't make much sense to set the device to 666 or
have udev put ACLs on it otherwise.

$ grep drm /lib/udev/rules.d/70-acl.rules 
SUBSYSTEM=="drm", KERNEL=="card*", ENV{ACL_MANAGE}="1"

cu
Ludwig

-- 
 (o_   Ludwig Nussel
 //\   
 V_/_  http://www.suse.de/
SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nuernberg)

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