From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-cys01nam02on0101.outbound.protection.outlook.com ([104.47.37.101]:1938 "EHLO NAM02-CY1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S966830AbeCSQMy (ORCPT ); Mon, 19 Mar 2018 12:12:54 -0400 From: Sasha Levin To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" CC: Liping Zhang , Pablo Neira Ayuso , Sasha Levin Subject: [PATCH AUTOSEL for 3.18 042/102] netfilter: ctnetlink: fix incorrect nf_ct_put during hash resize Date: Mon, 19 Mar 2018 16:12:24 +0000 Message-ID: <20180319161117.17833-42-alexander.levin@microsoft.com> References: <20180319161117.17833-1-alexander.levin@microsoft.com> In-Reply-To: <20180319161117.17833-1-alexander.levin@microsoft.com> Content-Language: en-US Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org List-ID: From: Liping Zhang [ Upstream commit fefa92679dbe0c613e62b6c27235dcfbe9640ad1 ] If nf_conntrack_htable_size was adjusted by the user during the ct dump operation, we may invoke nf_ct_put twice for the same ct, i.e. the "last" ct. This will cause the ct will be freed but still linked in hash buckets. It's very easy to reproduce the problem by the following commands: # while : ; do echo $RANDOM > /proc/sys/net/netfilter/nf_conntrack_buckets done # while : ; do conntrack -L done # iperf -s 127.0.0.1 & # iperf -c 127.0.0.1 -P 60 -t 36000 After a while, the system will hang like this: NMI watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [bash:20184] NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [iperf:20382] ... So at last if we find cb->args[1] is equal to "last", this means hash resize happened, then we can set cb->args[1] to 0 to fix the above issue. Fixes: d205dc40798d ("[NETFILTER]: ctnetlink: fix deadlock in table dumping= ") Signed-off-by: Liping Zhang Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- net/netfilter/nf_conntrack_netlink.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntr= ack_netlink.c index de9ea452dd60..4d69e924a0f1 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -828,8 +828,13 @@ ctnetlink_dump_table(struct sk_buff *skb, struct netli= nk_callback *cb) } out: local_bh_enable(); - if (last) + if (last) { + /* nf ct hash resize happened, now clear the leftover. */ + if ((struct nf_conn *)cb->args[1] =3D=3D last) + cb->args[1] =3D 0; + nf_ct_put(last); + } =20 return skb->len; } --=20 2.14.1