From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752110AbeE3LXI (ORCPT ); Wed, 30 May 2018 07:23:08 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:60959 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752509AbeE3LHG (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, "Xin Long" , "Florian Westphal" , "Pablo Neira Ayuso" , "Paolo Abeni" , syzbot+ddde1c7b7ff7442d7f2d@syzkaller.appspotmail.com Date: Wed, 30 May 2018 11:52:41 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 089/153] netfilter: drop outermost socket lock in getsockopt() 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: Paolo Abeni commit 01ea306f2ac2baff98d472da719193e738759d93 upstream. The Syzbot reported a possible deadlock in the netfilter area caused by rtnl lock, xt lock and socket lock being acquired with a different order on different code paths, leading to the following backtrace: Reviewed-by: Xin Long ====================================================== WARNING: possible circular locking dependency detected 4.15.0+ #301 Not tainted ------------------------------------------------------ syzkaller233489/4179 is trying to acquire lock: (rtnl_mutex){+.+.}, at: [<0000000048e996fd>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 but task is already holding lock: (&xt[i].mutex){+.+.}, at: [<00000000328553a2>] xt_find_table_lock+0x3e/0x3e0 net/netfilter/x_tables.c:1041 which lock already depends on the new lock. === Since commit 3f34cfae1230 ("netfilter: on sockopt() acquire sock lock only in the required scope"), we already acquire the socket lock in the innermost scope, where needed. In such commit I forgot to remove the outer-most socket lock from the getsockopt() path, this commit addresses the issues dropping it now. v1 -> v2: fix bad subj, added relavant 'fixes' tag Fixes: 22265a5c3c10 ("netfilter: xt_TEE: resolve oif using netdevice notifiers") Fixes: 202f59afd441 ("netfilter: ipt_CLUSTERIP: do not hold dev") Fixes: 3f34cfae1230 ("netfilter: on sockopt() acquire sock lock only in the required scope") Reported-by: syzbot+ddde1c7b7ff7442d7f2d@syzkaller.appspotmail.com Suggested-by: Florian Westphal Signed-off-by: Paolo Abeni Signed-off-by: Pablo Neira Ayuso Signed-off-by: Ben Hutchings --- net/ipv4/ip_sockglue.c | 7 +------ net/ipv6/ipv6_sockglue.c | 10 ++-------- 2 files changed, 3 insertions(+), 14 deletions(-) --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -1308,10 +1308,7 @@ int ip_getsockopt(struct sock *sk, int l if (get_user(len, optlen)) return -EFAULT; - lock_sock(sk); - err = nf_getsockopt(sk, PF_INET, optname, optval, - &len); - release_sock(sk); + err = nf_getsockopt(sk, PF_INET, optname, optval, &len); if (err >= 0) err = put_user(len, optlen); return err; @@ -1343,9 +1340,7 @@ int compat_ip_getsockopt(struct sock *sk if (get_user(len, optlen)) return -EFAULT; - lock_sock(sk); err = compat_nf_getsockopt(sk, PF_INET, optname, optval, &len); - release_sock(sk); if (err >= 0) err = put_user(len, optlen); return err; --- a/net/ipv6/ipv6_sockglue.c +++ b/net/ipv6/ipv6_sockglue.c @@ -1237,10 +1237,7 @@ int ipv6_getsockopt(struct sock *sk, int if (get_user(len, optlen)) return -EFAULT; - lock_sock(sk); - err = nf_getsockopt(sk, PF_INET6, optname, optval, - &len); - release_sock(sk); + err = nf_getsockopt(sk, PF_INET6, optname, optval, &len); if (err >= 0) err = put_user(len, optlen); } @@ -1280,10 +1277,7 @@ int compat_ipv6_getsockopt(struct sock * if (get_user(len, optlen)) return -EFAULT; - lock_sock(sk); - err = compat_nf_getsockopt(sk, PF_INET6, - optname, optval, &len); - release_sock(sk); + err = compat_nf_getsockopt(sk, PF_INET6, optname, optval, &len); if (err >= 0) err = put_user(len, optlen); }