From patchwork Wed Aug 15 13:36:08 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gustavo A. R. Silva" X-Patchwork-Id: 10566643 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 06C93139A for ; Wed, 15 Aug 2018 14:00:10 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E98FC2A7CA for ; Wed, 15 Aug 2018 14:00:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E77AF2A774; Wed, 15 Aug 2018 14:00:09 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7FCE02A6DF for ; Wed, 15 Aug 2018 14:00:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729287AbeHOQwZ (ORCPT ); Wed, 15 Aug 2018 12:52:25 -0400 Received: from gateway23.websitewelcome.com ([192.185.48.251]:49666 "EHLO gateway23.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729239AbeHOQwY (ORCPT ); Wed, 15 Aug 2018 12:52:24 -0400 X-Greylist: delayed 1418 seconds by postgrey-1.27 at vger.kernel.org; Wed, 15 Aug 2018 12:52:24 EDT Received: from cm15.websitewelcome.com (cm15.websitewelcome.com [100.42.49.9]) by gateway23.websitewelcome.com (Postfix) with ESMTP id 1AB8B32C76 for ; Wed, 15 Aug 2018 08:36:34 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id pvy7fdbGMbXuJpvyLf1Kr6; 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-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: 6 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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;