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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,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 D3828C4321D for ; Thu, 16 Aug 2018 19:30:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9C14721526 for ; Thu, 16 Aug 2018 19:30:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9C14721526 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 S1726326AbeHPWa5 (ORCPT ); Thu, 16 Aug 2018 18:30:57 -0400 Received: from gateway21.websitewelcome.com ([192.185.45.250]:20640 "EHLO gateway21.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725783AbeHPWa5 (ORCPT ); Thu, 16 Aug 2018 18:30:57 -0400 Received: from cm11.websitewelcome.com (cm11.websitewelcome.com [100.42.49.5]) by gateway21.websitewelcome.com (Postfix) with ESMTP id BB02D40111563 for ; Thu, 16 Aug 2018 14:30:36 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id qNyLfYY2GRPojqNyWf0xvU; Thu, 16 Aug 2018 14:30:36 -0500 X-Authority-Reason: nr=8 Received: from [189.250.72.226] (port=55558 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.91) (envelope-from ) id 1fqNyK-004E1u-T4; Thu, 16 Aug 2018 14:30:17 -0500 Date: Thu, 16 Aug 2018 14:30:15 -0500 From: "Gustavo A. R. Silva" To: VMware Graphics , Sinclair Yeh , Thomas Hellstrom , David Airlie Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] drm/vmwgfx: Fix potential Spectre v1 Message-ID: <20180816193015.GA12093@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: 189.250.72.226 X-Source-L: No X-Exim-ID: 1fqNyK-004E1u-T4 X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [189.250.72.226]:55558 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 arg.version is 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/vmwgfx/vmwgfx_execbuf.c:4526 vmw_execbuf_ioctl() warn: potential spectre issue 'copy_offset' [w] Fix this by sanitizing arg.version before using it to index copy_offset 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/vmwgfx/vmwgfx_execbuf.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c index 1f13457..ad91c6e 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c @@ -25,6 +25,7 @@ * **************************************************************************/ #include +#include #include "vmwgfx_drv.h" #include "vmwgfx_reg.h" @@ -4520,8 +4521,10 @@ int vmw_execbuf_ioctl(struct drm_device *dev, unsigned long data, return -EINVAL; } - if (arg.version > 1 && - copy_from_user(&arg.context_handle, + if (arg.version >= ARRAY_SIZE(copy_offset)) + return -EFAULT; + arg.version = array_index_nospec(arg.version, ARRAY_SIZE(copy_offset)); + if (copy_from_user(&arg.context_handle, (void __user *) (data + copy_offset[0]), copy_offset[arg.version - 1] - copy_offset[0]) != 0) -- 2.7.4