From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.us.es ([193.147.175.20]:44160 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752517AbeBTQjR (ORCPT ); Tue, 20 Feb 2018 11:39:17 -0500 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id 66360396278 for ; Tue, 20 Feb 2018 17:39:16 +0100 (CET) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 55FC6DA2CC for ; Tue, 20 Feb 2018 17:39:16 +0100 (CET) From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org Subject: [PATCH 03/19] netfilter: drop outermost socket lock in getsockopt() Date: Tue, 20 Feb 2018 17:38:50 +0100 Message-Id: <20180220163906.12380-4-pablo@netfilter.org> In-Reply-To: <20180220163906.12380-1-pablo@netfilter.org> References: <20180220163906.12380-1-pablo@netfilter.org> Sender: netdev-owner@vger.kernel.org List-ID: From: Paolo Abeni 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 --- net/ipv4/ip_sockglue.c | 7 +------ net/ipv6/ipv6_sockglue.c | 10 ++-------- 2 files changed, 3 insertions(+), 14 deletions(-) diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index 008be04ac1cc..9c41a0cef1a5 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -1567,10 +1567,7 @@ int ip_getsockopt(struct sock *sk, int level, 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; @@ -1602,9 +1599,7 @@ int compat_ip_getsockopt(struct sock *sk, int level, int optname, 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; diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c index d78d41fc4b1a..24535169663d 100644 --- a/net/ipv6/ipv6_sockglue.c +++ b/net/ipv6/ipv6_sockglue.c @@ -1367,10 +1367,7 @@ int ipv6_getsockopt(struct sock *sk, int level, int optname, 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); } @@ -1409,10 +1406,7 @@ int compat_ipv6_getsockopt(struct sock *sk, int level, int optname, 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); } -- 2.11.0