From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6323BC433E6 for ; Mon, 20 Jul 2020 15:42:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3B1442064B for ; Mon, 20 Jul 2020 15:42:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595259770; bh=iN43UrU09nwTp1zCVdClYerTQcxqUQ6fO53FIPvMZi8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=CjVuskzEcy9qqYt5FBoq4R4mnwTlGDcDU8nf0HwIhWHfbE0aYNIhol7tPj5yjDVoT vl9JyBmygd5bZKebUU4fr07vcJTo8CdnXN5uz6Uvo0YN9FkdJjbA6EKSHgXT6LTLln /ybIfAFLb+iNz+kF5jSNPPxgkoZ797i1ymI7tCxs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729524AbgGTPmh (ORCPT ); Mon, 20 Jul 2020 11:42:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:35574 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729597AbgGTPmh (ORCPT ); Mon, 20 Jul 2020 11:42:37 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 97D4420773; Mon, 20 Jul 2020 15:42:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595259756; bh=iN43UrU09nwTp1zCVdClYerTQcxqUQ6fO53FIPvMZi8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZIKK9+JDdlEWQBliQfA04yZ9Tscpfl/uec8geRbBFq0grRhPNUXnIFU1vLXR04FRt sQh1VyOmE6mchwgLHqvGW+yqq9XVmH2CVctQS7F7a3OLmrRYwMBFmUp1B0ghcxSKcN SGIiAHJ380U0wE6ILuFMOYHTZ/9SM3gTSYc5k3VM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Cameron Berkenpas , Peter Geis , Lu Fengqi , =?UTF-8?q?Dani=C3=ABl=20Sonck?= , Zhang Qiang , Thomas Lamprecht , Daniel Borkmann , Zefan Li , Tejun Heo , Roman Gushchin , Cong Wang , "David S. Miller" Subject: [PATCH 4.9 38/86] cgroup: fix cgroup_sk_alloc() for sk_clone_lock() Date: Mon, 20 Jul 2020 17:36:34 +0200 Message-Id: <20200720152755.083928761@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200720152753.138974850@linuxfoundation.org> References: <20200720152753.138974850@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Cong Wang [ Upstream commit ad0f75e5f57ccbceec13274e1e242f2b5a6397ed ] When we clone a socket in sk_clone_lock(), its sk_cgrp_data is copied, so the cgroup refcnt must be taken too. And, unlike the sk_alloc() path, sock_update_netprioidx() is not called here. Therefore, it is safe and necessary to grab the cgroup refcnt even when cgroup_sk_alloc is disabled. sk_clone_lock() is in BH context anyway, the in_interrupt() would terminate this function if called there. And for sk_alloc() skcd->val is always zero. So it's safe to factor out the code to make it more readable. The global variable 'cgroup_sk_alloc_disabled' is used to determine whether to take these reference counts. It is impossible to make the reference counting correct unless we save this bit of information in skcd->val. So, add a new bit there to record whether the socket has already taken the reference counts. This obviously relies on kmalloc() to align cgroup pointers to at least 4 bytes, ARCH_KMALLOC_MINALIGN is certainly larger than that. This bug seems to be introduced since the beginning, commit d979a39d7242 ("cgroup: duplicate cgroup reference when cloning sockets") tried to fix it but not compeletely. It seems not easy to trigger until the recent commit 090e28b229af ("netprio_cgroup: Fix unlimited memory leak of v2 cgroups") was merged. Fixes: bd1060a1d671 ("sock, cgroup: add sock->sk_cgroup") Reported-by: Cameron Berkenpas Reported-by: Peter Geis Reported-by: Lu Fengqi Reported-by: Daniël Sonck Reported-by: Zhang Qiang Tested-by: Cameron Berkenpas Tested-by: Peter Geis Tested-by: Thomas Lamprecht Cc: Daniel Borkmann Cc: Zefan Li Cc: Tejun Heo Cc: Roman Gushchin Signed-off-by: Cong Wang Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- include/linux/cgroup-defs.h | 6 ++++-- include/linux/cgroup.h | 4 +++- kernel/cgroup.c | 24 ++++++++++++++++++------ net/core/sock.c | 2 +- 4 files changed, 26 insertions(+), 10 deletions(-) --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -587,7 +587,8 @@ struct sock_cgroup_data { union { #ifdef __LITTLE_ENDIAN struct { - u8 is_data; + u8 is_data : 1; + u8 no_refcnt : 1; u8 padding; u16 prioidx; u32 classid; @@ -597,7 +598,8 @@ struct sock_cgroup_data { u32 classid; u16 prioidx; u8 padding; - u8 is_data; + u8 no_refcnt : 1; + u8 is_data : 1; } __packed; #endif u64 val; --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -657,6 +657,7 @@ extern spinlock_t cgroup_sk_update_lock; void cgroup_sk_alloc_disable(void); void cgroup_sk_alloc(struct sock_cgroup_data *skcd); +void cgroup_sk_clone(struct sock_cgroup_data *skcd); void cgroup_sk_free(struct sock_cgroup_data *skcd); static inline struct cgroup *sock_cgroup_ptr(struct sock_cgroup_data *skcd) @@ -670,7 +671,7 @@ static inline struct cgroup *sock_cgroup */ v = READ_ONCE(skcd->val); - if (v & 1) + if (v & 3) return &cgrp_dfl_root.cgrp; return (struct cgroup *)(unsigned long)v ?: &cgrp_dfl_root.cgrp; @@ -682,6 +683,7 @@ static inline struct cgroup *sock_cgroup #else /* CONFIG_CGROUP_DATA */ static inline void cgroup_sk_alloc(struct sock_cgroup_data *skcd) {} +static inline void cgroup_sk_clone(struct sock_cgroup_data *skcd) {} static inline void cgroup_sk_free(struct sock_cgroup_data *skcd) {} #endif /* CONFIG_CGROUP_DATA */ --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -6326,12 +6326,8 @@ void cgroup_sk_alloc_disable(void) 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)); + if (cgroup_sk_alloc_disabled) { + skcd->no_refcnt = 1; return; } @@ -6355,8 +6351,24 @@ void cgroup_sk_alloc(struct sock_cgroup_ rcu_read_unlock(); } +void cgroup_sk_clone(struct sock_cgroup_data *skcd) +{ + /* Socket clone path */ + if (skcd->val) { + /* + * We might be cloning a socket which is left in an empty + * cgroup and the cgroup might have already been rmdir'd. + * Don't use cgroup_get_live(). + */ + cgroup_get(sock_cgroup_ptr(skcd)); + } +} + void cgroup_sk_free(struct sock_cgroup_data *skcd) { + if (skcd->no_refcnt) + return; + cgroup_put(sock_cgroup_ptr(skcd)); } --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1533,7 +1533,7 @@ struct sock *sk_clone_lock(const struct newsk->sk_userlocks = sk->sk_userlocks & ~SOCK_BINDPORT_LOCK; sock_reset_flag(newsk, SOCK_DONE); - cgroup_sk_alloc(&newsk->sk_cgrp_data); + cgroup_sk_clone(&newsk->sk_cgrp_data); skb_queue_head_init(&newsk->sk_error_queue); filter = rcu_dereference_protected(newsk->sk_filter, 1);