Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751338AbbEYNuX (ORCPT ); Mon, 25 May 2015 09:50:23 -0400 Received: from mga02.intel.com ([134.134.136.20]:21624 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751026AbbEYNuW (ORCPT ); Mon, 25 May 2015 09:50:22 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.13,491,1427785200"; d="scan'208";a="731351382" From: Jani Nikula To: Andrey Ryabinin , David Airlie Cc: Ander Conselvan de Oliveira , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: Re: [PATCH] drm/atomic: fix out of bounds read in for_each_*_in_state helpers In-Reply-To: <87lhgcix4s.fsf@intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <1432549784-21966-1-git-send-email-a.ryabinin@samsung.com> <87oal8iyxh.fsf@intel.com> <556322E6.3020500@samsung.com> <87lhgcix4s.fsf@intel.com> User-Agent: Notmuch/0.19+112~g77230b0 (http://notmuchmail.org) Emacs/24.4.1 (x86_64-pc-linux-gnu) Date: Mon, 25 May 2015 16:52:31 +0300 Message-ID: <87iobgix28.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2433 Lines: 67 On Mon, 25 May 2015, Jani Nikula wrote: > On Mon, 25 May 2015, Andrey Ryabinin wrote: >> On 05/25/2015 04:12 PM, Jani Nikula wrote: >>> On Mon, 25 May 2015, Andrey Ryabinin wrote: >>>> for_each_*_in_state validate array index after >>>> access to array elements, thus perform out of bounds read. >>>> >>>> Fix this by validating index in the first place and read >>>> array element iff validation was successful. >>>> >>>> Fixes: df63b9994eaf ("drm/atomic: Add for_each_{connector,crtc,plane}_in_state helper macros") >>>> Signed-off-by: Andrey Ryabinin >>>> --- >>>> include/drm/drm_atomic.h | 24 ++++++++++++------------ >>>> 1 file changed, 12 insertions(+), 12 deletions(-) >>>> >>>> diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h >>>> index c1571034..3f13b91 100644 >>>> --- a/include/drm/drm_atomic.h >>>> +++ b/include/drm/drm_atomic.h >>>> @@ -77,26 +77,26 @@ int __must_check drm_atomic_async_commit(struct drm_atomic_state *state); >>>> >>>> #define for_each_connector_in_state(state, connector, connector_state, __i) \ >>>> for ((__i) = 0; \ >>>> - (connector) = (state)->connectors[__i], \ >>>> - (connector_state) = (state)->connector_states[__i], \ >>>> - (__i) < (state)->num_connector; \ >>>> + (__i) < (state)->num_connector && \ >>>> + ((connector) = (state)->connectors[__i], \ >>>> + (connector_state) = (state)->connector_states[__i], 1); \ >>> >>> This will stop at the first NULL connector/connector_state. Similarly >>> for the loops below. >>> >> >> This will stop iff (__i) >= (state)->num_connector, because the result of expression: >> ((connector) = (state)->connectors[__i], (connector_state) = (state)->connector_states[__i], 1) >> is always 1. > > Why do you think it'll always be 1? That might be because there's the 1 at the end. *blush*. I do wonder if this is too subtle in general, or if it's just too subtle for me. BR, Jani. > > BR, > Jani. > > >> >> > > -- > Jani Nikula, Intel Open Source Technology Center -- Jani Nikula, Intel Open Source Technology Center -- 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/