From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:49800 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934522AbcA0SNu (ORCPT ); Wed, 27 Jan 2016 13:13:50 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dave Jones , Eric Dumazet , "David S. Miller" Subject: [PATCH 4.4 39/67] ipv6: tcp: add rcu locking in tcp_v6_send_synack() Date: Wed, 27 Jan 2016 10:12:33 -0800 Message-Id: <20160127180911.980691416@linuxfoundation.org> In-Reply-To: <20160127180907.419868641@linuxfoundation.org> References: <20160127180907.419868641@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 3e4006f0b86a5ae5eb0e8215f9a9e1db24506977 ] 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 Signed-off-by: Greg Kroah-Hartman --- net/ipv6/tcp_ipv6.c | 2 ++ 1 file changed, 2 insertions(+) --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -462,8 +462,10 @@ static int tcp_v6_send_synack(const stru if (np->repflow && ireq->pktopts) fl6->flowlabel = ip6_flowlabel(ipv6_hdr(ireq->pktopts)); + rcu_read_lock(); err = ip6_xmit(sk, skb, fl6, rcu_dereference(np->opt), np->tclass); + rcu_read_unlock(); err = net_xmit_eval(err); }