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 D2765C04A68 for ; Wed, 27 Jul 2022 16:31:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237666AbiG0QbR (ORCPT ); Wed, 27 Jul 2022 12:31:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34496 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237446AbiG0Qal (ORCPT ); Wed, 27 Jul 2022 12:30:41 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7DCBA5247E; Wed, 27 Jul 2022 09:25:28 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 4C6DC617EF; Wed, 27 Jul 2022 16:25:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 55C4BC433C1; Wed, 27 Jul 2022 16:25:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658939116; bh=HaPcLU8OTjq/O0rBKkVeU0xDiBOTbO2unGt7nLpjxW8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qd3j45M7StFg0v59aBfnVpx7lnyVh1kVNSr2Yt8ssgGx7EikG2HJvBki1RPoAsVWz gLnjwMKhQq5WW8DDQO9gzjxdW+Dd24V9uzF36xNMR8HHCz6VuN/koNfv4w9B9p4OiL 1AnX5BzJtpwBeDY7FXiMM+4A2gvVKB6512sA6UO4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Kuniyuki Iwashima , "David S. Miller" , Sasha Levin Subject: [PATCH 4.19 07/62] ip: Fix data-races around sysctl_ip_fwd_use_pmtu. Date: Wed, 27 Jul 2022 18:10:16 +0200 Message-Id: <20220727161004.448768084@linuxfoundation.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220727161004.175638564@linuxfoundation.org> References: <20220727161004.175638564@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: linux-kernel@vger.kernel.org From: Kuniyuki Iwashima [ Upstream commit 60c158dc7b1f0558f6cadd5b50d0386da0000d50 ] While reading sysctl_ip_fwd_use_pmtu, it can be changed concurrently. Thus, we need to add READ_ONCE() to its readers. Fixes: f87c10a8aa1e ("ipv4: introduce ip_dst_mtu_maybe_forward and protect forwarding path against pmtu spoofing") Signed-off-by: Kuniyuki Iwashima Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- include/net/ip.h | 2 +- net/ipv4/route.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/include/net/ip.h b/include/net/ip.h index d1a4efedbc03..471463bfe6f9 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -402,7 +402,7 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst, struct net *net = dev_net(dst->dev); unsigned int mtu; - if (net->ipv4.sysctl_ip_fwd_use_pmtu || + if (READ_ONCE(net->ipv4.sysctl_ip_fwd_use_pmtu) || ip_mtu_locked(dst) || !forwarding) return dst_mtu(dst); diff --git a/net/ipv4/route.c b/net/ipv4/route.c index d7f17581df7d..57e2316529d0 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1419,7 +1419,7 @@ u32 ip_mtu_from_fib_result(struct fib_result *res, __be32 daddr) struct net_device *dev = nh->nh_dev; u32 mtu = 0; - if (dev_net(dev)->ipv4.sysctl_ip_fwd_use_pmtu || + if (READ_ONCE(dev_net(dev)->ipv4.sysctl_ip_fwd_use_pmtu) || fi->fib_metrics->metrics[RTAX_LOCK - 1] & (1 << RTAX_MTU)) mtu = fi->fib_mtu; -- 2.35.1