From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2C932C04EBD for ; Tue, 16 Oct 2018 10:42:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D908020881 for ; Tue, 16 Oct 2018 10:42:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D908020881 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=embeddedor.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727007AbeJPSbr (ORCPT ); Tue, 16 Oct 2018 14:31:47 -0400 Received: from gateway20.websitewelcome.com ([192.185.66.3]:36364 "EHLO gateway20.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726553AbeJPSbr (ORCPT ); Tue, 16 Oct 2018 14:31:47 -0400 X-Greylist: delayed 1505 seconds by postgrey-1.27 at vger.kernel.org; Tue, 16 Oct 2018 14:31:47 EDT Received: from cm15.websitewelcome.com (cm15.websitewelcome.com [100.42.49.9]) by gateway20.websitewelcome.com (Postfix) with ESMTP id 95FFC400D85E4 for ; Tue, 16 Oct 2018 04:56:07 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id CM4wgC4Kttz4jCM54gJqog; Tue, 16 Oct 2018 04:56:07 -0500 X-Authority-Reason: nr=8 Received: from lfbn-1-466-13.w86-245.abo.wanadoo.fr ([86.245.173.13]:35248 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.91) (envelope-from ) id 1gCM4v-000I8X-MA; Tue, 16 Oct 2018 04:55:54 -0500 Date: Tue, 16 Oct 2018 11:55:49 +0200 From: "Gustavo A. R. Silva" To: Maarten Lankhorst , Maxime Ripard , Sean Paul , David Airlie Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] drm/bufs: Fix Spectre v1 vulnerability Message-ID: <20181016095549.GA23586@embeddedor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.24 (2015-08-30) X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 86.245.173.13 X-Source-L: No X-Exim-ID: 1gCM4v-000I8X-MA X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: lfbn-1-466-13.w86-245.abo.wanadoo.fr (embeddedor) [86.245.173.13]:35248 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 11 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org idx can be indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: drivers/gpu/drm/drm_bufs.c:1420 drm_legacy_freebufs() warn: potential spectre issue 'dma->buflist' [r] (local cap) Fix this by sanitizing idx before using it to index dma->buflist Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 Cc: stable@vger.kernel.org Signed-off-by: Gustavo A. R. Silva --- drivers/gpu/drm/drm_bufs.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/drm_bufs.c b/drivers/gpu/drm/drm_bufs.c index 7412aca..d7d10ca 100644 --- a/drivers/gpu/drm/drm_bufs.c +++ b/drivers/gpu/drm/drm_bufs.c @@ -36,6 +36,8 @@ #include #include "drm_legacy.h" +#include + static struct drm_map_list *drm_find_matching_map(struct drm_device *dev, struct drm_local_map *map) { @@ -1417,6 +1419,7 @@ int drm_legacy_freebufs(struct drm_device *dev, void *data, idx, dma->buf_count - 1); return -EINVAL; } + idx = array_index_nospec(idx, dma->buf_count); buf = dma->buflist[idx]; if (buf->file_priv != file_priv) { DRM_ERROR("Process %d freeing buffer not owned\n", -- 2.7.4