From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764117AbcINTxD (ORCPT ); Wed, 14 Sep 2016 15:53:03 -0400 Received: from gum.cmpxchg.org ([85.214.110.215]:34512 "EHLO gum.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751061AbcINTw7 (ORCPT ); Wed, 14 Sep 2016 15:52:59 -0400 From: Johannes Weiner To: Andrew Morton , Tejun Heo , "David S. Miller" Cc: Michal Hocko , Vladimir Davydov , linux-mm@kvack.org, cgroups@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: [PATCH 2/3] cgroup: duplicate cgroup reference when cloning sockets Date: Wed, 14 Sep 2016 15:48:45 -0400 Message-Id: <20160914194846.11153-2-hannes@cmpxchg.org> X-Mailer: git-send-email 2.9.3 In-Reply-To: <20160914194846.11153-1-hannes@cmpxchg.org> References: <20160914194846.11153-1-hannes@cmpxchg.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Johannes Weiner When a socket is cloned, the associated sock_cgroup_data is duplicated but not its reference on the cgroup. As a result, the cgroup reference count will underflow when both sockets are destroyed later on. Fixes: bd1060a1d671 ("sock, cgroup: add sock->sk_cgroup") Cc: # 4.5+ Signed-off-by: Johannes Weiner --- kernel/cgroup.c | 6 ++++++ net/core/sock.c | 5 ++++- 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 0c4db7908264..b0d727d26fc7 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -6297,6 +6297,12 @@ void cgroup_sk_alloc(struct sock_cgroup_data *skcd) if (cgroup_sk_alloc_disabled) return; + /* Socket clone path */ + if (skcd->val) { + cgroup_get(sock_cgroup_ptr(skcd)); + return; + } + rcu_read_lock(); while (true) { diff --git a/net/core/sock.c b/net/core/sock.c index 51a730485649..038e660ef844 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1340,7 +1340,6 @@ static struct sock *sk_prot_alloc(struct proto *prot, gfp_t priority, if (!try_module_get(prot->owner)) goto out_free_sec; sk_tx_queue_clear(sk); - cgroup_sk_alloc(&sk->sk_cgrp_data); } return sk; @@ -1400,6 +1399,7 @@ struct sock *sk_alloc(struct net *net, int family, gfp_t priority, sock_net_set(sk, net); atomic_set(&sk->sk_wmem_alloc, 1); + cgroup_sk_alloc(&sk->sk_cgrp_data); sock_update_classid(&sk->sk_cgrp_data); sock_update_netprioidx(&sk->sk_cgrp_data); } @@ -1544,6 +1544,9 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority) newsk->sk_priority = 0; newsk->sk_incoming_cpu = raw_smp_processor_id(); atomic64_set(&newsk->sk_cookie, 0); + + cgroup_sk_alloc(&newsk->sk_cgrp_data); + /* * Before updating sk_refcnt, we must commit prior changes to memory * (Documentation/RCU/rculist_nulls.txt for details) -- 2.9.3