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=-3.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 1FED9C04AB1 for ; Thu, 9 May 2019 14:13:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EEF9C2085A for ; Thu, 9 May 2019 14:13:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726913AbfEIONq (ORCPT ); Thu, 9 May 2019 10:13:46 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:46960 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726700AbfEIONL (ORCPT ); Thu, 9 May 2019 10:13:11 -0400 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1hOjnI-000127-Lg; Thu, 09 May 2019 15:13:08 +0100 Received: from ben by deadeye with local (Exim 4.92) (envelope-from ) id 1hOjnI-0006MF-DT; Thu, 09 May 2019 15:13:08 +0100 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, Denis Kirjanov , "Eric Dumazet" , "David S. Miller" Date: Thu, 09 May 2019 15:08:17 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 06/10] ipv4: fix a race in update_or_create_fnhe() In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.67-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit caa415270c732505240bb60171c44a7838c555e8 upstream. nh_exceptions is effectively used under rcu, but lacks proper barriers. Between kzalloc() and setting of nh->nh_exceptions(), we need a proper memory barrier. Signed-off-by: Eric Dumazet Fixes: 4895c771c7f00 ("ipv4: Add FIB nexthop exceptions.") Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- include/net/ip_fib.h | 2 +- net/ipv4/fib_semantics.c | 8 +++++--- net/ipv4/route.c | 6 +++--- 3 files changed, 9 insertions(+), 7 deletions(-) --- a/include/net/ip_fib.h +++ b/include/net/ip_fib.h @@ -89,7 +89,7 @@ struct fib_nh { int nh_saddr_genid; struct rtable __rcu * __percpu *nh_pcpu_rth_output; struct rtable __rcu *nh_rth_input; - struct fnhe_hash_bucket *nh_exceptions; + struct fnhe_hash_bucket __rcu *nh_exceptions; }; /* --- a/net/ipv4/fib_semantics.c +++ b/net/ipv4/fib_semantics.c @@ -157,9 +157,12 @@ static void rt_fibinfo_free(struct rtabl static void free_nh_exceptions(struct fib_nh *nh) { - struct fnhe_hash_bucket *hash = nh->nh_exceptions; + struct fnhe_hash_bucket *hash; int i; + hash = rcu_dereference_protected(nh->nh_exceptions, 1); + if (!hash) + return; for (i = 0; i < FNHE_HASH_SIZE; i++) { struct fib_nh_exception *fnhe; @@ -206,8 +209,7 @@ static void free_fib_info_rcu(struct rcu change_nexthops(fi) { if (nexthop_nh->nh_dev) dev_put(nexthop_nh->nh_dev); - if (nexthop_nh->nh_exceptions) - free_nh_exceptions(nexthop_nh); + free_nh_exceptions(nexthop_nh); rt_fibinfo_free_cpus(nexthop_nh->nh_pcpu_rth_output); rt_fibinfo_free(&nexthop_nh->nh_rth_input); } endfor_nexthops(fi); --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -635,12 +635,12 @@ static void update_or_create_fnhe(struct spin_lock_bh(&fnhe_lock); - hash = nh->nh_exceptions; + hash = rcu_dereference(nh->nh_exceptions); if (!hash) { hash = kzalloc(FNHE_HASH_SIZE * sizeof(*hash), GFP_ATOMIC); if (!hash) goto out_unlock; - nh->nh_exceptions = hash; + rcu_assign_pointer(nh->nh_exceptions, hash); } hash += hval; @@ -1293,7 +1293,7 @@ static void ip_del_fnhe(struct fib_nh *n static struct fib_nh_exception *find_exception(struct fib_nh *nh, __be32 daddr) { - struct fnhe_hash_bucket *hash = nh->nh_exceptions; + struct fnhe_hash_bucket *hash = rcu_dereference(nh->nh_exceptions); struct fib_nh_exception *fnhe; u32 hval;