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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9658AC3527D for ; Tue, 12 Apr 2022 08:07:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353295AbiDLIDY (ORCPT ); Tue, 12 Apr 2022 04:03:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1356897AbiDLHjc (ORCPT ); Tue, 12 Apr 2022 03:39:32 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 79354532C1; Tue, 12 Apr 2022 00:10:21 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id C8355B81B55; Tue, 12 Apr 2022 07:10:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 46844C385A5; Tue, 12 Apr 2022 07:10:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649747418; bh=RUwbLHotjbX+UqZxx8hmxHOaCEpsBQyNX+ZzVXZ4Gls=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ty+DWUsm7NbNwdAU0XROdA+WO8CYdw5FIczrDinBiKzR+k2w8GKpjlLPZztQLOZ06 MHCa8wQFdeTStubqKKBhTxGusOHldQxd/GuVt2hjzSy88JC6brPHjXYcAkAgjVh8sO nslpecqJvkMkI5GNKZrVJgtUHl1y2vevz3AFjvYA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.17 073/343] tcp: Dont acquire inet_listen_hashbucket::lock with disabled BH. Date: Tue, 12 Apr 2022 08:28:11 +0200 Message-Id: <20220412062953.208339537@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220412062951.095765152@linuxfoundation.org> References: <20220412062951.095765152@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sebastian Andrzej Siewior [ Upstream commit 4f9bf2a2f5aacf988e6d5e56b961ba45c5a25248 ] Commit 9652dc2eb9e40 ("tcp: relax listening_hash operations") removed the need to disable bottom half while acquiring listening_hash.lock. There are still two callers left which disable bottom half before the lock is acquired. On PREEMPT_RT the softirqs are preemptible and local_bh_disable() acts as a lock to ensure that resources, that are protected by disabling bottom halves, remain protected. This leads to a circular locking dependency if the lock acquired with disabled bottom halves is also acquired with enabled bottom halves followed by disabling bottom halves. This is the reverse locking order. It has been observed with inet_listen_hashbucket::lock: local_bh_disable() + spin_lock(&ilb->lock): inet_listen() inet_csk_listen_start() sk->sk_prot->hash() := inet_hash() local_bh_disable() __inet_hash() spin_lock(&ilb->lock); acquire(&ilb->lock); Reverse order: spin_lock(&ilb2->lock) + local_bh_disable(): tcp_seq_next() listening_get_next() spin_lock(&ilb2->lock); acquire(&ilb2->lock); tcp4_seq_show() get_tcp4_sock() sock_i_ino() read_lock_bh(&sk->sk_callback_lock); acquire(softirq_ctrl) // <---- whoops acquire(&sk->sk_callback_lock) Drop local_bh_disable() around __inet_hash() which acquires listening_hash->lock. Split inet_unhash() and acquire the listen_hashbucket lock without disabling bottom halves; the inet_ehash lock with disabled bottom halves. Reported-by: Mike Galbraith Signed-off-by: Sebastian Andrzej Siewior Link: https://lkml.kernel.org/r/12d6f9879a97cd56c09fb53dee343cbb14f7f1f7.camel@gmx.de Link: https://lkml.kernel.org/r/X9CheYjuXWc75Spa@hirez.programming.kicks-ass.net Link: https://lore.kernel.org/r/YgQOebeZ10eNx1W6@linutronix.de Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/ipv4/inet_hashtables.c | 53 ++++++++++++++++++++++--------------- net/ipv6/inet6_hashtables.c | 5 +--- 2 files changed, 33 insertions(+), 25 deletions(-) diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index 30ab717ff1b8..17440840a791 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -637,7 +637,9 @@ int __inet_hash(struct sock *sk, struct sock *osk) int err = 0; if (sk->sk_state != TCP_LISTEN) { + local_bh_disable(); inet_ehash_nolisten(sk, osk, NULL); + local_bh_enable(); return 0; } WARN_ON(!sk_unhashed(sk)); @@ -669,45 +671,54 @@ int inet_hash(struct sock *sk) { int err = 0; - if (sk->sk_state != TCP_CLOSE) { - local_bh_disable(); + if (sk->sk_state != TCP_CLOSE) err = __inet_hash(sk, NULL); - local_bh_enable(); - } return err; } EXPORT_SYMBOL_GPL(inet_hash); -void inet_unhash(struct sock *sk) +static void __inet_unhash(struct sock *sk, struct inet_listen_hashbucket *ilb) { - struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo; - struct inet_listen_hashbucket *ilb = NULL; - spinlock_t *lock; - if (sk_unhashed(sk)) return; - if (sk->sk_state == TCP_LISTEN) { - ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)]; - lock = &ilb->lock; - } else { - lock = inet_ehash_lockp(hashinfo, sk->sk_hash); - } - spin_lock_bh(lock); - if (sk_unhashed(sk)) - goto unlock; - if (rcu_access_pointer(sk->sk_reuseport_cb)) reuseport_stop_listen_sock(sk); if (ilb) { + struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo; + inet_unhash2(hashinfo, sk); ilb->count--; } __sk_nulls_del_node_init_rcu(sk); sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1); -unlock: - spin_unlock_bh(lock); +} + +void inet_unhash(struct sock *sk) +{ + struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo; + + if (sk_unhashed(sk)) + return; + + if (sk->sk_state == TCP_LISTEN) { + struct inet_listen_hashbucket *ilb; + + ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)]; + /* Don't disable bottom halves while acquiring the lock to + * avoid circular locking dependency on PREEMPT_RT. + */ + spin_lock(&ilb->lock); + __inet_unhash(sk, ilb); + spin_unlock(&ilb->lock); + } else { + spinlock_t *lock = inet_ehash_lockp(hashinfo, sk->sk_hash); + + spin_lock_bh(lock); + __inet_unhash(sk, NULL); + spin_unlock_bh(lock); + } } EXPORT_SYMBOL_GPL(inet_unhash); diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c index 4514444e96c8..4740afecf7c6 100644 --- a/net/ipv6/inet6_hashtables.c +++ b/net/ipv6/inet6_hashtables.c @@ -333,11 +333,8 @@ int inet6_hash(struct sock *sk) { int err = 0; - if (sk->sk_state != TCP_CLOSE) { - local_bh_disable(); + if (sk->sk_state != TCP_CLOSE) err = __inet_hash(sk, NULL); - local_bh_enable(); - } return err; } -- 2.35.1