From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756267Ab3L2DCz (ORCPT ); Sat, 28 Dec 2013 22:02:55 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:55034 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751968Ab3L2CJv (ORCPT ); Sat, 28 Dec 2013 21:09:51 -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" , "Hannes Frederic Sowa" , "Eric Dumazet" , "David S. Miller" Date: Sun, 29 Dec 2013 03:08:44 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 170/185] ipv6: fix possible seqlock deadlock in ip6_finish_output2 In-Reply-To: X-SA-Exim-Connect-IP: 31.18.200.85 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 3.2.54-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Hannes Frederic Sowa [ Upstream commit 7f88c6b23afbd31545c676dea77ba9593a1a14bf ] IPv6 stats are 64 bits and thus are protected with a seqlock. By not disabling bottom-half we could deadlock here if we don't disable bh and a softirq reentrantly updates the same mib. Cc: Eric Dumazet Signed-off-by: Hannes Frederic Sowa Acked-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- net/ipv6/ip6_output.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 97675bf..d3fde7e 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -144,8 +144,8 @@ static int ip6_finish_output2(struct sk_buff *skb) return res; } rcu_read_unlock(); - IP6_INC_STATS_BH(dev_net(dst->dev), - ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES); + IP6_INC_STATS(dev_net(dst->dev), + ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES); kfree_skb(skb); return -EINVAL; }