From patchwork Fri Feb 17 07:39:28 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Westphal X-Patchwork-Id: 729048 X-Patchwork-Delegate: pablo@netfilter.org Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3vPlLw4LbQz9ryj for ; Fri, 17 Feb 2017 18:40:56 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755846AbdBQHkr (ORCPT ); Fri, 17 Feb 2017 02:40:47 -0500 Received: from Chamillionaire.breakpoint.cc ([146.0.238.67]:45236 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755643AbdBQHkr (ORCPT ); Fri, 17 Feb 2017 02:40:47 -0500 Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.84_2) (envelope-from ) id 1ced8a-0002UP-LF; Fri, 17 Feb 2017 08:39:28 +0100 Date: Fri, 17 Feb 2017 08:39:28 +0100 From: Florian Westphal To: Daniel J Blueman Cc: Netdev , "David S. Miller" , "Eric W. Biederman" , David Ahern , Jan Beulich , Eric Dumazet , netfilter-devel@vger.kernel.org, pablo@netfilter.org Subject: Re: [4.9.10] ip_route_me_harder() reading off-slab Message-ID: <20170217073928.GA25854@breakpoint.cc> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: netfilter-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Daniel J Blueman wrote: [ CC nf-devel, pablo ] > When booting a VM in libvirt/KVM attached to a local bridge and KASAN > enabled on 4.9.10, we see a stream of KASAN warnings about off-slab > access [1]. > > Let me know if you'd like more debug. Does this patch help? Subject: [PATCH nf] netfilter: use skb_to_full_sk in ip_route_me_harder inet_sk(skb->sk) is illegal in case skb is attached to request socket. Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of listener") Reported by: Daniel J Blueman Signed-off-by: Florian Westphal Tested-by: Daniel J Blueman --- net/ipv4/netfilter.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/net/ipv4/netfilter.c b/net/ipv4/netfilter.c index b3cc1335adbc..c0cc6aa8cfaa 100644 --- a/net/ipv4/netfilter.c +++ b/net/ipv4/netfilter.c @@ -23,7 +23,8 @@ int ip_route_me_harder(struct net *net, struct sk_buff *skb, unsigned int addr_t struct rtable *rt; struct flowi4 fl4 = {}; __be32 saddr = iph->saddr; - __u8 flags = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0; + const struct sock *sk = skb_to_full_sk(skb); + __u8 flags = sk ? inet_sk_flowi_flags(sk) : 0; struct net_device *dev = skb_dst(skb)->dev; unsigned int hh_len; @@ -40,7 +41,7 @@ int ip_route_me_harder(struct net *net, struct sk_buff *skb, unsigned int addr_t fl4.daddr = iph->daddr; fl4.saddr = saddr; fl4.flowi4_tos = RT_TOS(iph->tos); - fl4.flowi4_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0; + fl4.flowi4_oif = sk ? sk->sk_bound_dev_if : 0; if (!fl4.flowi4_oif) fl4.flowi4_oif = l3mdev_master_ifindex(dev); fl4.flowi4_mark = skb->mark; @@ -61,7 +62,7 @@ int ip_route_me_harder(struct net *net, struct sk_buff *skb, unsigned int addr_t xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) { struct dst_entry *dst = skb_dst(skb); skb_dst_set(skb, NULL); - dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), skb->sk, 0); + dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), sk, 0); if (IS_ERR(dst)) return PTR_ERR(dst); skb_dst_set(skb, dst);