From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754133AbcHVIir (ORCPT ); Mon, 22 Aug 2016 04:38:47 -0400 Received: from mga05.intel.com ([192.55.52.43]:24868 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750839AbcHVIip (ORCPT ); Mon, 22 Aug 2016 04:38:45 -0400 X-Greylist: delayed 575 seconds by postgrey-1.27 at vger.kernel.org; Mon, 22 Aug 2016 04:38:45 EDT X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.28,559,1464678000"; d="scan'208";a="1045237044" From: Jani Nikula To: Daniel Vetter , Heinrich Schuchardt Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: Re: [PATCH 1/1] drm: avoid exposing kernel stack in compat_drm_getstats In-Reply-To: <20160822072718.GC6232@phenom.ffwll.local> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <1471802179-2886-1-git-send-email-xypron.glpk@gmx.de> <20160822072718.GC6232@phenom.ffwll.local> User-Agent: Notmuch/0.22.1+63~g648dcc7 (https://notmuchmail.org) Emacs/24.4.1 (x86_64-pc-linux-gnu) Date: Mon, 22 Aug 2016 11:29:07 +0300 Message-ID: <87fupxurzg.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 On Mon, 22 Aug 2016, Daniel Vetter wrote: > On Sun, Aug 21, 2016 at 07:56:19PM +0200, Heinrich Schuchardt wrote: >> The C standard does not specify the size of the integer used >> to store an enum. Hence in structure drm_stats32_t alignment >> bytes may exist. >> >> To avoid exposing bytes from the kernel stack it is >> necessary to initialize variable s32 completely. >> >> Signed-off-by: Heinrich Schuchardt > > Applied to drm-misc, thanks. > -Daniel > >> --- >> drivers/gpu/drm/drm_ioc32.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/drivers/gpu/drm/drm_ioc32.c b/drivers/gpu/drm/drm_ioc32.c >> index 57676f8..32a489b 100644 >> --- a/drivers/gpu/drm/drm_ioc32.c >> +++ b/drivers/gpu/drm/drm_ioc32.c >> @@ -346,6 +346,7 @@ static int compat_drm_getstats(struct file *file, unsigned int cmd, >> struct drm_stats __user *stats; >> int i, err; >> >> + memset(&s32, 0, sizeof(drm_stats32_t)); For future reference, memset(&s32, 0, sizeof(s32)); is the better approach, avoiding problems if the type of s32 ever changes. BR, Jani. >> stats = compat_alloc_user_space(sizeof(*stats)); >> if (!stats) >> return -EFAULT; >> -- >> 2.1.4 >> >> _______________________________________________ >> dri-devel mailing list >> dri-devel@lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Jani Nikula, Intel Open Source Technology Center