From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756218Ab2GCHHP (ORCPT ); Tue, 3 Jul 2012 03:07:15 -0400 Received: from ja.ssi.bg ([178.16.129.10]:46306 "EHLO ja.ssi.bg" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750910Ab2GCHHM (ORCPT ); Tue, 3 Jul 2012 03:07:12 -0400 Date: Tue, 3 Jul 2012 10:12:41 +0300 (EEST) From: Julian Anastasov To: Xiaotian Feng cc: netdev@vger.kernel.org, lvs-devel@vger.kernel.org, netfilter-devel@vger.kernel.org, netfilter@vger.kernel.org, coreteam@netfilter.org, linux-kernel@vger.kernel.org, Xiaotian Feng , Wensong Zhang , Simon Horman , Pablo Neira Ayuso , Patrick McHardy , "David S. Miller" Subject: Re: [RFC PATCH net-next] ipvs: add missing lock in ip_vs_ftp_init_conn() In-Reply-To: <1340890587-8169-1-git-send-email-xtfeng@gmail.com> Message-ID: References: <1340890587-8169-1-git-send-email-xtfeng@gmail.com> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Thu, 28 Jun 2012, Xiaotian Feng wrote: > We met a kernel panic in 2.6.32.43 kernel: > > [2680191.848044] IPVS: ip_vs_conn_hash(): request for already hashed, called from run_timer_softirq+0x175/0x1d0 > > [2680311.849009] general protection fault: 0000 [#1] SMP > [2680311.853001] RIP: 0010:[] [] ip_vs_conn_expire+0xdc/0x2f0 > [2680311.853001] RSP: 0018:ffff880028303e70 EFLAGS: 00010202 > [2680311.853001] RAX: dead000000200200 RBX: ffff8801aad00b80 RCX: 0000000000001d90 > [2680311.853001] RDX: dead000000100100 RSI: 000000004fd59800 RDI: ffff8801aad00c08 > > [2680311.853001] Call Trace: > [2680311.853001] > [2680311.853001] [] ? ip_vs_conn_expire+0x0/0x2f0 > [2680311.853001] [] run_timer_softirq+0x175/0x1d0 > [2680311.853001] [] ? lapic_next_event+0x18/0x20 > [2680311.853001] [] __do_softirq+0xb3/0x150 > [2680311.853001] [] call_softirq+0x1c/0x30 > [2680311.853001] [] do_softirq+0x4a/0x80 > [2680311.853001] [] irq_exit+0x77/0x80 > [2680311.853001] [] smp_apic_timer_interrupt+0x6c/0xa0 > [2680311.853001] [] apic_timer_interrupt+0x13/0x20 > [2680311.853001] > [2680311.853001] [] ? mwait_idle+0x52/0x70 > [2680311.853001] [] ? enter_idle+0x20/0x30 > [2680311.853001] [] ? cpu_idle+0x52/0x80 > [2680311.853001] [] ? start_secondary+0x19d/0x280 > > rax and rdx is LIST_POISON1 and LIST_POISON2, so kernel is list_del() on an already deleted > connection and result the general protect fault. > > The "request for already hashed" warning, told us someone might change the connection flags > incorrectly, like described in commit aea9d711, it changes the connection flags, but doesn't > put the connection back to the list. So ip_vs_conn_hash() throw a warning and return. > Later, when ip_vs_conn_expire fire again, ip_vs_conn_unhash() will find the HASHED connection > and list_del() it, then kernel panic happened. > > After code review, the only chance that kernel change connection flag without protection is > in ip_vs_ftp_init_conn(). > > Signed-off-by: Xiaotian Feng > Cc: Wensong Zhang > Cc: Simon Horman > Cc: Julian Anastasov > Cc: Pablo Neira Ayuso > Cc: Patrick McHardy > Cc: "David S. Miller" For the fix below: Acked-by: Julian Anastasov Simon, the change looks ok. ip_vs_ftp_init_conn is called from context where cp->lock is not locked (no double lock), so it should be safe for the backup. Only that the comment is not specifying that we fix a problem in the backup server. > --- > net/netfilter/ipvs/ip_vs_ftp.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/net/netfilter/ipvs/ip_vs_ftp.c b/net/netfilter/ipvs/ip_vs_ftp.c > index b20b29c..c2bc264 100644 > --- a/net/netfilter/ipvs/ip_vs_ftp.c > +++ b/net/netfilter/ipvs/ip_vs_ftp.c > @@ -65,8 +65,10 @@ static int ip_vs_ftp_pasv; > static int > ip_vs_ftp_init_conn(struct ip_vs_app *app, struct ip_vs_conn *cp) > { > + spin_lock(&cp->lock); > /* We use connection tracking for the command connection */ > cp->flags |= IP_VS_CONN_F_NFCT; > + spin_unlock(&cp->lock); > return 0; > } > > -- > 1.7.1 Regards -- Julian Anastasov