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From: Chris Wilson <chris@chris-wilson.co.uk>
Subject: Re: [PATCH 1/2] drm/i915: fix integer overflow in i915_gem_execbuffer2()
To: Xi Wang <xi.wang@gmail.com>
Cc: Keith Packard <keithp@keithp.com>, Daniel Vetter <daniel.vetter@ffwll.ch>,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
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Date: Fri, 06 Apr 2012 14:54:05 +0100
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On Fri, 6 Apr 2012 09:46:46 -0400, Xi Wang <xi.wang@gmail.com> wrote:
> On Apr 6, 2012, at 9:36 AM, Chris Wilson wrote:
> 
> > On Fri,  6 Apr 2012 08:58:18 -0400, Xi Wang <xi.wang@gmail.com> wrote:
> >> A large args->buffer_count from userspace may overflow the allocation
> >> size, leading to out-of-bounds access.
> >> 
> >> Use kmalloc_array() to avoid that.
> > 
> > I can safely say that exec list larger than 4GiB is going to be an
> > illegal operation and would rather the ioctl failed outright with
> > EINVAL.
> 
> On 32-bit platform?

On any platform. The largest it can legally be is a few tens of megabytes.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre