From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933186AbcBIADy (ORCPT ); Mon, 8 Feb 2016 19:03:54 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:59863 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932332AbcBHXyk (ORCPT ); Mon, 8 Feb 2016 18:54:40 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Eric Dumazet" , "David S. Miller" , "Dave Jones" Date: Mon, 08 Feb 2016 23:53:51 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 39/87] ipv6: tcp: add rcu locking in tcp_v6_send_synack() In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:a11:96ff:fe28:a980 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.77-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit 3e4006f0b86a5ae5eb0e8215f9a9e1db24506977 upstream. When first SYNACK is sent, we already hold rcu_read_lock(), but this is not true if a SYNACK is retransmitted, as a timer (soft) interrupt does not hold rcu_read_lock() Fixes: 45f6fad84cc30 ("ipv6: add complete rcu protection around np->opt") Reported-by: Dave Jones Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- net/ipv6/tcp_ipv6.c | 2 ++ 1 file changed, 2 insertions(+) --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -513,8 +513,10 @@ static int tcp_v6_send_synack(struct soc __tcp_v6_send_check(skb, &treq->loc_addr, &treq->rmt_addr); ipv6_addr_copy(&fl6.daddr, &treq->rmt_addr); + rcu_read_lock(); err = ip6_xmit(sk, skb, &fl6, rcu_dereference(np->opt), np->tclass); + rcu_read_unlock(); err = net_xmit_eval(err); }