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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 CC175C43387 for ; Tue, 18 Dec 2018 16:14:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A354821841 for ; Tue, 18 Dec 2018 16:14:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727126AbeLRQOs (ORCPT ); Tue, 18 Dec 2018 11:14:48 -0500 Received: from gateway22.websitewelcome.com ([192.185.47.79]:19418 "EHLO gateway22.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726471AbeLRQOs (ORCPT ); Tue, 18 Dec 2018 11:14:48 -0500 Received: from cm10.websitewelcome.com (cm10.websitewelcome.com [100.42.49.4]) by gateway22.websitewelcome.com (Postfix) with ESMTP id 1D9232768C for ; Tue, 18 Dec 2018 10:14:47 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id ZI19gT5XB2PzOZI19gDbKx; Tue, 18 Dec 2018 10:14:47 -0600 X-Authority-Reason: nr=8 Received: from [189.250.106.44] (port=57630 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.91) (envelope-from ) id 1gZI18-000jNo-FI; Tue, 18 Dec 2018 10:14:46 -0600 Date: Tue, 18 Dec 2018 10:14:45 -0600 From: "Gustavo A. R. Silva" To: Jens Axboe Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] loop: Fix potential Spectre v1 vulnerability Message-ID: <20181218161445.GA10311@embeddedor> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) 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: 189.250.106.44 X-Source-L: No X-Exim-ID: 1gZI18-000jNo-FI X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [189.250.106.44]:57630 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 3 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 type 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/block/loop.c:1208 loop_set_status() warn: potential spectre issue 'xfer_funcs' [r] (local cap) Fix this by sanitizing type before using it to index xfer_funcs. 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/block/loop.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 0939f36548c9..015d255f451b 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -83,6 +83,8 @@ #include +#include + static DEFINE_IDR(loop_index_idr); static DEFINE_MUTEX(loop_ctl_mutex); @@ -1205,6 +1207,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) err = -EINVAL; goto out_unfreeze; } + type = array_index_nospec(type, MAX_LO_CRYPT); xfer = xfer_funcs[type]; if (xfer == NULL) { err = -EINVAL; -- 2.19.2