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=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 7EDB0C43387 for ; Fri, 21 Dec 2018 20:49:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4B5F321929 for ; Fri, 21 Dec 2018 20:49:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390573AbeLUUtH (ORCPT ); Fri, 21 Dec 2018 15:49:07 -0500 Received: from gateway30.websitewelcome.com ([192.185.149.4]:32175 "EHLO gateway30.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730307AbeLUUtG (ORCPT ); Fri, 21 Dec 2018 15:49:06 -0500 Received: from cm16.websitewelcome.com (cm16.websitewelcome.com [100.42.49.19]) by gateway30.websitewelcome.com (Postfix) with ESMTP id 874D4CFD5 for ; Fri, 21 Dec 2018 14:49:05 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id aRjFgEOFO4FKpaRjFgjOJv; Fri, 21 Dec 2018 14:49:05 -0600 X-Authority-Reason: nr=8 Received: from [189.250.106.44] (port=33332 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.91) (envelope-from ) id 1gaRjE-0004yz-Q0; Fri, 21 Dec 2018 14:49:04 -0600 Date: Fri, 21 Dec 2018 14:49:01 -0600 From: "Gustavo A. R. Silva" To: Alexei Starovoitov , Daniel Borkmann , "David S. Miller" Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] net: core: Fix Spectre v1 vulnerability Message-ID: <20181221204901.GA30045@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: 1gaRjE-0004yz-Q0 X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [189.250.106.44]:33332 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 5 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 flen 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: net/core/filter.c:1101 bpf_check_classic() warn: potential spectre issue 'filter' [w] Fix this by sanitizing flen before using it to index filter at line 1101: switch (filter[flen - 1].code) { and through pc at line 1040: const struct sock_filter *ftest = &filter[pc]; 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 Signed-off-by: Gustavo A. R. Silva --- net/core/filter.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/core/filter.c b/net/core/filter.c index 447dd1bad31f..8ec4337256ed 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -73,6 +73,7 @@ #include #include #include +#include /** * sk_filter_trim_cap - run a packet through a socket filter @@ -1035,6 +1036,7 @@ static int bpf_check_classic(const struct sock_filter *filter, bool anc_found; int pc; + flen = array_index_nospec(flen, BPF_MAXINSNS + 1); /* Check the filter code now */ for (pc = 0; pc < flen; pc++) { const struct sock_filter *ftest = &filter[pc]; -- 2.20.1