From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Steinar H. Gunderson" , Valentijn Sessink , YOSHIFUJI Hideaki , Eric Dumazet , Hannes Frederic Sowa , "David S. Miller" Subject: [PATCH 3.11 09/25] ipv6: reset dst.expires value when clearing expire flag Date: Mon, 18 Nov 2013 10:40:38 -0800 Message-Id: <20131118184035.168853423@linuxfoundation.org> In-Reply-To: <20131118184032.248465920@linuxfoundation.org> References: <20131118184032.248465920@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.11-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hannes Frederic Sowa [ Upstream commit 01ba16d6ec85a1ec4669c75513a76b61ec53ee50 ] 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 and rt6_clean_expires did assign NULL to it. 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 Acked-by: Eric Dumazet Tested-by: Valentijn Sessink Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- include/net/ip6_fib.h | 1 + 1 file changed, 1 insertion(+) --- a/include/net/ip6_fib.h +++ b/include/net/ip6_fib.h @@ -165,6 +165,7 @@ static inline struct inet6_dev *ip6_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)