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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,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 AEEB4C11F93 for ; Mon, 12 Jul 2021 08:39:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A30166127C for ; Mon, 12 Jul 2021 08:39:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378847AbhGLIl1 (ORCPT ); Mon, 12 Jul 2021 04:41:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:35484 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350312AbhGLHuu (ORCPT ); Mon, 12 Jul 2021 03:50:50 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C06B1619B9; Mon, 12 Jul 2021 07:44:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626075864; bh=4dzgCyh8BYXAmzhq/UXO6qhbFFREt8XwUHGT9V8zmVo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qHg3jPbTv1caFLCxOk4GpyhvBNgVxyYonxcTrVV5lrKlCZeTgaOtyXO5b0aCMHAIC bYF1LQw6V/bUDuDDvSAUqUByeHupFi6Ock2HY56a48YP+3tvtnaAtbLQlIAiR5LmYo Hdex2ZtQB5s2Z8gX981xQKXlmzlH/0av29b8FmfY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Taehee Yoo , Cong Wang , "David S. Miller" , Sasha Levin , syzbot+7d941e89dd48bcf42573@syzkaller.appspotmail.com Subject: [PATCH 5.13 398/800] rtnetlink: avoid RCU read lock when holding RTNL Date: Mon, 12 Jul 2021 08:07:01 +0200 Message-Id: <20210712061009.507557079@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210712060912.995381202@linuxfoundation.org> References: <20210712060912.995381202@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: Cong Wang [ Upstream commit a100243d95a60d74ae9bb9df1f5f2192e9aed6a7 ] When we call af_ops->set_link_af() we hold a RCU read lock as we retrieve af_ops from the RCU protected list, but this is unnecessary because we already hold RTNL lock, which is the writer lock for protecting rtnl_af_ops, so it is safer than RCU read lock. Similar for af_ops->validate_link_af(). This was not a problem until we begin to take mutex lock down the path of ->set_link_af() in __ipv6_dev_mc_dec() recently. We can just drop the RCU read lock there and assert RTNL lock. Reported-and-tested-by: syzbot+7d941e89dd48bcf42573@syzkaller.appspotmail.com Fixes: 63ed8de4be81 ("mld: add mc_lock for protecting per-interface mld data") Tested-by: Taehee Yoo Signed-off-by: Cong Wang Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/core/rtnetlink.c | 26 +++++++------------------- net/ipv4/devinet.c | 4 ++-- 2 files changed, 9 insertions(+), 21 deletions(-) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index ec931b080156..c6e75bd0035d 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -543,7 +543,9 @@ static const struct rtnl_af_ops *rtnl_af_lookup(const int family) { const struct rtnl_af_ops *ops; - list_for_each_entry_rcu(ops, &rtnl_af_ops, list) { + ASSERT_RTNL(); + + list_for_each_entry(ops, &rtnl_af_ops, list) { if (ops->family == family) return ops; } @@ -2274,27 +2276,18 @@ static int validate_linkmsg(struct net_device *dev, struct nlattr *tb[]) nla_for_each_nested(af, tb[IFLA_AF_SPEC], rem) { const struct rtnl_af_ops *af_ops; - rcu_read_lock(); af_ops = rtnl_af_lookup(nla_type(af)); - if (!af_ops) { - rcu_read_unlock(); + if (!af_ops) return -EAFNOSUPPORT; - } - if (!af_ops->set_link_af) { - rcu_read_unlock(); + if (!af_ops->set_link_af) return -EOPNOTSUPP; - } if (af_ops->validate_link_af) { err = af_ops->validate_link_af(dev, af); - if (err < 0) { - rcu_read_unlock(); + if (err < 0) return err; - } } - - rcu_read_unlock(); } } @@ -2868,17 +2861,12 @@ static int do_setlink(const struct sk_buff *skb, nla_for_each_nested(af, tb[IFLA_AF_SPEC], rem) { const struct rtnl_af_ops *af_ops; - rcu_read_lock(); - BUG_ON(!(af_ops = rtnl_af_lookup(nla_type(af)))); err = af_ops->set_link_af(dev, af, extack); - if (err < 0) { - rcu_read_unlock(); + if (err < 0) goto errout; - } - rcu_read_unlock(); status |= DO_SETLINK_NOTIFY; } } diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c index 1c6429c353a9..73721a4448bd 100644 --- a/net/ipv4/devinet.c +++ b/net/ipv4/devinet.c @@ -1955,7 +1955,7 @@ static int inet_validate_link_af(const struct net_device *dev, struct nlattr *a, *tb[IFLA_INET_MAX+1]; int err, rem; - if (dev && !__in_dev_get_rcu(dev)) + if (dev && !__in_dev_get_rtnl(dev)) return -EAFNOSUPPORT; err = nla_parse_nested_deprecated(tb, IFLA_INET_MAX, nla, @@ -1981,7 +1981,7 @@ static int inet_validate_link_af(const struct net_device *dev, static int inet_set_link_af(struct net_device *dev, const struct nlattr *nla, struct netlink_ext_ack *extack) { - struct in_device *in_dev = __in_dev_get_rcu(dev); + struct in_device *in_dev = __in_dev_get_rtnl(dev); struct nlattr *a, *tb[IFLA_INET_MAX+1]; int rem; -- 2.30.2