linux-kernel - Re: [PATCH] drm/i915: bounds check execbuffer relocations

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Message-ID: <20130311205251.GB31324@cantiga.alporthouse.com>
Date:	Mon, 11 Mar 2013 20:52:51 +0000
From:	Chris Wilson <chris@...is-wilson.co.uk>
To:	Kees Cook <keescook@...omium.org>
Cc:	linux-kernel@...r.kernel.org,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	David Airlie <airlied@...ux.ie>,
	dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] drm/i915: bounds check execbuffer relocations

On Mon, Mar 11, 2013 at 12:27:16PM -0700, Kees Cook wrote:
> It is possible to wrap the counter used to allocate the buffer for
> relocation copies. This could lead to heap writing overflows.

Seems a sensible check, just in the wrong location. You need to do the
checking upfront in validate_exec_list() so that the error condition is
always hit and that the limits are applied consistently to all
execbuffers.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre
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