From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753195AbeE3L2p (ORCPT ); Wed, 30 May 2018 07:28:45 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:60958 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752453AbeE3LHG (ORCPT ); Wed, 30 May 2018 07:07:06 -0400 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, "Florian Westphal" , "Pablo Neira Ayuso" , "Cong Wang" , "Eric Dumazet" Date: Wed, 30 May 2018 11:52:41 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 090/153] netfilter: ipt_CLUSTERIP: fix a refcount bug in clusterip_config_find_get() In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 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 3.2.102-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Cong Wang commit db93a3632b0f8773a3899e04a3a3e0aa7a26eb46 upstream. In clusterip_config_find_get() we hold RCU read lock so it could run concurrently with clusterip_config_entry_put(), as a result, the refcnt could go back to 1 from 0, which leads to a double list_del()... Just replace refcount_inc() with refcount_inc_not_zero(), as for c->refcount. Fixes: d73f33b16883 ("netfilter: CLUSTERIP: RCU conversion") Cc: Eric Dumazet Cc: Pablo Neira Ayuso Cc: Florian Westphal Signed-off-by: Cong Wang Reviewed-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso [bwh: Backported to 3.2: s/refcount/atomic/] Signed-off-by: Ben Hutchings --- net/ipv4/netfilter/ipt_CLUSTERIP.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/net/ipv4/netfilter/ipt_CLUSTERIP.c +++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c @@ -135,8 +135,12 @@ clusterip_config_find_get(__be32 cluster if (c) { if (unlikely(!atomic_inc_not_zero(&c->refcount))) c = NULL; - else if (entry) - atomic_inc(&c->entries); + else if (entry) { + if (unlikely(!atomic_inc_not_zero(&c->entries))) { + clusterip_config_put(c); + c = NULL; + } + } } rcu_read_unlock_bh();