Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754721Ab3CKXQM (ORCPT ); Mon, 11 Mar 2013 19:16:12 -0400 Received: from mail-ia0-f182.google.com ([209.85.210.182]:64018 "EHLO mail-ia0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754132Ab3CKXQJ (ORCPT ); Mon, 11 Mar 2013 19:16:09 -0400 Date: Tue, 12 Mar 2013 00:16:01 +0100 From: Daniel Vetter To: Kees Cook Cc: linux-kernel@vger.kernel.org, Daniel Vetter , David Airlie , dri-devel@lists.freedesktop.org Subject: Re: [PATCH v2] drm/i915: clarify reasoning for the access_ok call Message-ID: <20130311231601.GD3872@bremse> Mail-Followup-To: Kees Cook , linux-kernel@vger.kernel.org, David Airlie , dri-devel@lists.freedesktop.org References: <20130311213735.GA22493@www.outflux.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130311213735.GA22493@www.outflux.net> X-Operating-System: Linux bremse 3.8.0-rc6+ User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1876 Lines: 53 On Mon, Mar 11, 2013 at 02:37:35PM -0700, Kees Cook wrote: > This clarifies the comment above the access_ok check so a missing > VERIFY_READ doesn't alarm anyone. > > Signed-off-by: Kees Cook > Cc: Daniel Vetter > --- > v2: > - rewrote comment, thanks to Chris Wilson Queued for -next, thanks for the patch. Fyi I prefer the patch changelog in the actual commit message so that it gets recorded in git. Usually it's not that interesting, but sometimes knowning the history of a patch is really important. I've fixed this while applying. -Daniel > --- > drivers/gpu/drm/i915/i915_gem_execbuffer.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c > index bf7ceca..89c4039 100644 > --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c > +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c > @@ -751,7 +751,11 @@ validate_exec_list(struct drm_i915_gem_exec_object2 *exec, > > length = exec[i].relocation_count * > sizeof(struct drm_i915_gem_relocation_entry); > - /* we may also need to update the presumed offsets */ > + /* > + * We must check that the entire relocation array is safe > + * to read, but since we may need to update the presumed > + * offsets during execution, check for full write access. > + */ > if (!access_ok(VERIFY_WRITE, ptr, length)) > return -EFAULT; > > -- > 1.7.9.5 > > > -- > Kees Cook > Chrome OS Security -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/