From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id Jec1MIxBGVukbgAAmS7hNA ; Thu, 07 Jun 2018 14:31:17 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 0376C6063F; Thu, 7 Jun 2018 14:31:16 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id 522F9608CA; Thu, 7 Jun 2018 14:31:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 522F9608CA Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933684AbeFGOaV (ORCPT + 25 others); Thu, 7 Jun 2018 10:30:21 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:39420 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933065AbeFGOJK (ORCPT ); Thu, 7 Jun 2018 10:09:10 -0400 Received: from [148.252.241.226] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1fQvbA-0005a0-JT; Thu, 07 Jun 2018 15:09:08 +0100 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1fQvb7-00033S-G5; Thu, 07 Jun 2018 15:09:05 +0100 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, "Cong Wang" , "Pablo Neira Ayuso" , "Florian Westphal" , "Eric Dumazet" Date: Thu, 07 Jun 2018 15:05:21 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 235/410] netfilter: ipt_CLUSTERIP: fix a refcount bug in clusterip_config_find_get() In-Reply-To: X-SA-Exim-Connect-IP: 148.252.241.226 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.57-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 3.16: 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 @@ -147,8 +147,12 @@ clusterip_config_find_get(struct net *ne 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();