Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754962Ab3CKVhn (ORCPT ); Mon, 11 Mar 2013 17:37:43 -0400 Received: from smtp.outflux.net ([198.145.64.163]:39593 "EHLO smtp.outflux.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754907Ab3CKVhl (ORCPT ); Mon, 11 Mar 2013 17:37:41 -0400 Date: Mon, 11 Mar 2013 14:37:35 -0700 From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Daniel Vetter , David Airlie , dri-devel@lists.freedesktop.org Subject: [PATCH v2] drm/i915: clarify reasoning for the access_ok call Message-ID: <20130311213735.GA22493@www.outflux.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-HELO: www.outflux.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1367 Lines: 41 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 --- 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 -- 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/