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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 ACC27C433FE for ; Sun, 6 Dec 2020 11:43:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6EF7723110 for ; Sun, 6 Dec 2020 11:43:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729035AbgLFLmt (ORCPT ); Sun, 6 Dec 2020 06:42:49 -0500 Received: from mail.kernel.org ([198.145.29.99]:41906 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727924AbgLFLmp (ORCPT ); Sun, 6 Dec 2020 06:42:45 -0500 From: Greg Kroah-Hartman Authentication-Results: mail.kernel.org; dkim=permerror (bad message/signature format) To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Maria Pasechnik , Antoine Tenart , Jakub Kicinski Subject: [PATCH 5.4 23/39] net: ip6_gre: set dev->hard_header_len when using header_ops Date: Sun, 6 Dec 2020 12:17:27 +0100 Message-Id: <20201206111555.783347806@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201206111554.677764505@linuxfoundation.org> References: <20201206111554.677764505@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Antoine Tenart [ Upstream commit 832ba596494b2c9eac7760259eff2d8b7dcad0ee ] syzkaller managed to crash the kernel using an NBMA ip6gre interface. I could reproduce it creating an NBMA ip6gre interface and forwarding traffic to it: skbuff: skb_under_panic: text:ffffffff8250e927 len:148 put:44 head:ffff8c03c7a33 ------------[ cut here ]------------ kernel BUG at net/core/skbuff.c:109! Call Trace: skb_push+0x10/0x10 ip6gre_header+0x47/0x1b0 neigh_connected_output+0xae/0xf0 ip6gre tunnel provides its own header_ops->create, and sets it conditionally when initializing the tunnel in NBMA mode. When header_ops->create is used, dev->hard_header_len should reflect the length of the header created. Otherwise, when not used, dev->needed_headroom should be used. Fixes: eb95f52fc72d ("net: ipv6_gre: Fix GRO to work on IPv6 over GRE tap") Cc: Maria Pasechnik Signed-off-by: Antoine Tenart Link: https://lore.kernel.org/r/20201130161911.464106-1-atenart@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/ipv6/ip6_gre.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -1120,8 +1120,13 @@ static void ip6gre_tnl_link_config_route return; if (rt->dst.dev) { - dev->needed_headroom = rt->dst.dev->hard_header_len + - t_hlen; + unsigned short dst_len = rt->dst.dev->hard_header_len + + t_hlen; + + if (t->dev->header_ops) + dev->hard_header_len = dst_len; + else + dev->needed_headroom = dst_len; if (set_mtu) { dev->mtu = rt->dst.dev->mtu - t_hlen; @@ -1146,7 +1151,12 @@ static int ip6gre_calc_hlen(struct ip6_t tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen; t_hlen = tunnel->hlen + sizeof(struct ipv6hdr); - tunnel->dev->needed_headroom = LL_MAX_HEADER + t_hlen; + + if (tunnel->dev->header_ops) + tunnel->dev->hard_header_len = LL_MAX_HEADER + t_hlen; + else + tunnel->dev->needed_headroom = LL_MAX_HEADER + t_hlen; + return t_hlen; }