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,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 D571DC4646D for ; Wed, 15 Aug 2018 13:36:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8A6BB215B2 for ; Wed, 15 Aug 2018 13:36:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8A6BB215B2 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 S1729336AbeHOQ2q (ORCPT ); Wed, 15 Aug 2018 12:28:46 -0400 Received: from gateway30.websitewelcome.com ([192.185.193.11]:28670 "EHLO gateway30.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729287AbeHOQ2q (ORCPT ); Wed, 15 Aug 2018 12:28:46 -0400 Received: from cm15.websitewelcome.com (cm15.websitewelcome.com [100.42.49.9]) by gateway30.websitewelcome.com (Postfix) with ESMTP id 1A71C4749C for ; Wed, 15 Aug 2018 08:36:34 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id pvy7fdbGLbXuJpvyLf1KrB; Wed, 15 Aug 2018 08:36:33 -0500 X-Authority-Reason: nr=8 Received: from [189.250.37.72] (port=57088 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.91) (envelope-from ) id 1fpvy6-001yoE-QT; Wed, 15 Aug 2018 08:36:10 -0500 Date: Wed, 15 Aug 2018 08:36:08 -0500 From: "Gustavo A. R. Silva" To: Alexander Viro Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] statfs: fix potential Spectre v1 Message-ID: <20180815133608.GA27979@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: 189.250.37.72 X-Source-L: No X-Exim-ID: 1fpvy6-001yoE-QT X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [189.250.37.72]:57088 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 7 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 user_params.request 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: fs/statfs.c:908 __do_sys_fsinfo() warn: potential spectre issue 'fsinfo_buffer_sizes' [r] Fix this by sanitizing user_params.request before using it to index fsinfo_buffer_sizes 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 --- fs/statfs.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/statfs.c b/fs/statfs.c index f714f05..d74a60a 100644 --- a/fs/statfs.c +++ b/fs/statfs.c @@ -11,6 +11,7 @@ #include #include #include +#include #include "internal.h" static int flags_by_mnt(int mnt_flags) @@ -886,6 +887,8 @@ SYSCALL_DEFINE5(fsinfo, return -EINVAL; if (user_params.request >= FSINFO_ATTR__NR) return -EOPNOTSUPP; + user_params.request = array_index_nospec(user_params.request, + FSINFO_ATTR__NR); params.at_flags = user_params.at_flags; params.request = user_params.request; params.Nth = user_params.Nth; -- 2.7.4