From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: (ipt_log_packet, sb_add) 3.6.0-rc2 kernel panic - not syncing; Fatal exception in interrupt Date: Mon, 03 Sep 2012 00:53:05 +0200 Message-ID: <1346626385.2563.44.camel@edumazet-glaptop> References: <20120821134921.behn76vzvhczf3gc@m.safari.iki.fi> <20120902122008.jgdhwowbuke6by7h@m.safari.iki.fi> <20120902132834.GB7456@breakpoint.cc> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Sami Farin , netdev@vger.kernel.org, e1000-devel@lists.sourceforge.net To: Florian Westphal Return-path: Received: from mail-wi0-f172.google.com ([209.85.212.172]:46628 "EHLO mail-wi0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754788Ab2IBWxM (ORCPT ); Sun, 2 Sep 2012 18:53:12 -0400 Received: by wicr5 with SMTP id r5so3495278wic.1 for ; Sun, 02 Sep 2012 15:53:10 -0700 (PDT) In-Reply-To: <20120902132834.GB7456@breakpoint.cc> Sender: netdev-owner@vger.kernel.org List-ID: From: Eric Dumazet On Sun, 2012-09-02 at 15:28 +0200, Florian Westphal wrote: > Sami Farin wrote: > > I get this panic every 1-2 days. > > Also with 7a611e69b26069a511d9d5251c6a28af6c521121 (commit before 3.6.0-rc4). > > Could you please post iptables-save output? > My guess is you're using NFLOG in INPUT? > > If so, I bet its caused by the tcp early demux stuff. > Does that crash go away with ip_early_demux sysctl off? > > My guess is its assigning skb->sk with TIMEWAIT sockets, which > would explain the crash. Yes thats probably the reason. First I thought changing demux to not do the lookup of TIMEWAIT slot in __inet_lookup_established(), then it sounds not optimal to redo the full lookup for ESTABLISHED sockets later in TCP stack. So it seems we should fix xt_LOG instead Thanks Florian ! [PATCH] xt_LOG: take care of timewait sockets Sami Farin reported crashes in xt_LOG because it assumes skb->sk is a full blown socket. But with TCP early demux, we can have skb->sk pointing to a timewait socket. Diagnosed-by: Florian Westphal Reported-by: Sami Farin Signed-off-by: Eric Dumazet --- net/netfilter/xt_LOG.c | 33 +++++++++++++++++---------------- 1 file changed, 17 insertions(+), 16 deletions(-) diff --git a/net/netfilter/xt_LOG.c b/net/netfilter/xt_LOG.c index ff5f75f..2a4f969 100644 --- a/net/netfilter/xt_LOG.c +++ b/net/netfilter/xt_LOG.c @@ -145,6 +145,19 @@ static int dump_tcp_header(struct sbuff *m, const struct sk_buff *skb, return 0; } +static void dump_sk_uid_gid(struct sbuff *m, struct sock *sk) +{ + if (!sk || sk->sk_state == TCP_TIME_WAIT) + return; + + read_lock_bh(&sk->sk_callback_lock); + if (sk->sk_socket && sk->sk_socket->file) + sb_add(m, "UID=%u GID=%u ", + sk->sk_socket->file->f_cred->fsuid, + sk->sk_socket->file->f_cred->fsgid); + read_unlock_bh(&sk->sk_callback_lock); +} + /* One level of recursion won't kill us */ static void dump_ipv4_packet(struct sbuff *m, const struct nf_loginfo *info, @@ -361,14 +374,8 @@ static void dump_ipv4_packet(struct sbuff *m, } /* Max length: 15 "UID=4294967295 " */ - if ((logflags & XT_LOG_UID) && !iphoff && skb->sk) { - read_lock_bh(&skb->sk->sk_callback_lock); - if (skb->sk->sk_socket && skb->sk->sk_socket->file) - sb_add(m, "UID=%u GID=%u ", - skb->sk->sk_socket->file->f_cred->fsuid, - skb->sk->sk_socket->file->f_cred->fsgid); - read_unlock_bh(&skb->sk->sk_callback_lock); - } + if ((logflags & XT_LOG_UID) && !iphoff) + dump_sk_uid_gid(m, skb->sk); /* Max length: 16 "MARK=0xFFFFFFFF " */ if (!iphoff && skb->mark) @@ -717,14 +724,8 @@ static void dump_ipv6_packet(struct sbuff *m, } /* Max length: 15 "UID=4294967295 " */ - if ((logflags & XT_LOG_UID) && recurse && skb->sk) { - read_lock_bh(&skb->sk->sk_callback_lock); - if (skb->sk->sk_socket && skb->sk->sk_socket->file) - sb_add(m, "UID=%u GID=%u ", - skb->sk->sk_socket->file->f_cred->fsuid, - skb->sk->sk_socket->file->f_cred->fsgid); - read_unlock_bh(&skb->sk->sk_callback_lock); - } + if ((logflags & XT_LOG_UID) && recurse) + dump_sk_uid_gid(m, skb->sk); /* Max length: 16 "MARK=0xFFFFFFFF " */ if (!recurse && skb->mark)