From mboxrd@z Thu Jan 1 00:00:00 1970 From: Valentijn Sessink Subject: Re: [PATCH net 1/2] ipv6: reset dst.expires value when clearing expire flag Date: Thu, 24 Oct 2013 09:47:41 +0200 Message-ID: <5268D09D.8070103@blub.net> References: <20131024054816.GB5973@order.stressinduktion.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit To: netdev@vger.kernel.org Return-path: Received: from filter.openoffice.nl ([144.76.204.185]:37674 "EHLO filter.openoffice.nl" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1753711Ab3JXHxp (ORCPT ); Thu, 24 Oct 2013 03:53:45 -0400 Received: from localhost (localhost [127.0.0.1]) by filter.openoffice.nl (Postfix) with ESMTP id EF7D1800D7 for ; Thu, 24 Oct 2013 09:47:31 +0200 (CEST) Received: from filter.openoffice.nl ([127.0.0.1]) by localhost (filter.openoffice.nl [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id PG7tdAY2rLiD for ; Thu, 24 Oct 2013 09:47:29 +0200 (CEST) Received: from blub.net (unknown [IPv6:2001:7b8:1529:0:5054:ff:fe70:c2c4]) by filter.openoffice.nl (Postfix) with ESMTP id DB653800D5 for ; Thu, 24 Oct 2013 09:47:28 +0200 (CEST) Received: from [IPv6:2001:1af8:ff03:3:219:66ff:fe26:6dd] (unknown [IPv6:2001:1af8:ff03:3:219:66ff:fe26:6dd]) by blub.net (Postfix) with ESMTPSA id 7907230013B for ; Thu, 24 Oct 2013 09:47:28 +0200 (CEST) In-Reply-To: <20131024054816.GB5973@order.stressinduktion.org> Sender: netdev-owner@vger.kernel.org List-ID: On 24-10-13 07:48, Hannes Frederic Sowa wrote: > On receiving a packet too big icmp error we update the expire value by > calling rt6_update_expires. This function uses dst_set_expires which is > implemented that it can only reduce the expiration value of the dst entry. > > If we insert new routing non-expiry information into the ipv6 fib where > we already have a matching rt6_info we only clear the RTF_EXPIRES flag > in rt6i_flags and leave the dst.expires value as is. > > When new mtu information arrives for that cached dst_entry we again > call dst_set_expires. This time it won't update the dst.expire value > because we left the dst.expire value intact from the last update. So > dst_set_expires won't touch dst.expires. > > Fix this by resetting dst.expires when clearing the RTF_EXPIRE flag. > dst_set_expires checks for a zero expiration and updates the > dst.expires. > > In the past this (not updating dst.expires) was necessary because > dst.expire was placed in a union with the dst_entry *from reference. So > an update on the value would have caused page faults. This split happend > in ecd9883724b78cc72ed92c98bcb1a46c764fff21 ("ipv6: fix race condition > regarding dst->expires and dst->from"). > > Reported-by: Steinar H. Gunderson > Reported-by: Valentijn Sessink > Cc: YOSHIFUJI Hideaki > Signed-off-by: Hannes Frederic Sowa > --- > I would propose this patch for -stable. > > include/net/ip6_fib.h | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h > index 48ec25a..5e661a9 100644 > --- a/include/net/ip6_fib.h > +++ b/include/net/ip6_fib.h > @@ -165,6 +165,7 @@ static inline struct inet6_dev *ip6_dst_idev(struct dst_entry *dst) > static inline void rt6_clean_expires(struct rt6_info *rt) > { > rt->rt6i_flags &= ~RTF_EXPIRES; > + rt->dst.expires = 0; > } > > static inline void rt6_set_expires(struct rt6_info *rt, unsigned long expires) > Tested-by: Valentijn Sessink