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=-16.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,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 C016DC4161D for ; Wed, 12 May 2021 19:49:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 893CC61421 for ; Wed, 12 May 2021 19:49:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1382815AbhELTrz (ORCPT ); Wed, 12 May 2021 15:47:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:51904 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352677AbhELSD7 (ORCPT ); Wed, 12 May 2021 14:03:59 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1FE4D6143A; Wed, 12 May 2021 18:02:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1620842570; bh=NxRr3i/3FfdnK/KAHIiXOLrAkGgYPUD+efpTLGlFqX4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vEt+pP136ssI4AaYaSSHE8/ZuVLLDyoR9ifNtWwr99SYQ3VnypXWUnn/SMoZC0EeH HCzHRr6La8xKYoczNxc2+Vs1iPNhtpqNHD68ZolFyMuVZcRE6I/6eZdMgZZd1YHoJR ZIODsrZZYiNwlxx2T46PDLk74yKjWpNl6TCIYahCoWuSK2EcNr7EktIQO6J9XUrY43 ue0dqu5CL8kGZtriOFEboE6yt0YPBfMBCQy8kItcUISOahaWWoEoT6san9tsW8SBFW J48UDVJ9Qz24wLcTcccAJKQFpBYaULQ5Jit6WLuc/UaFxOSz1rJRU8P6R6/uWvZOAC HuMbHfgkjL90w== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Zhang Zhengming , Zhao Lei , Wang Xiaogang , Nikolay Aleksandrov , "David S . Miller" , Sasha Levin , bridge@lists.linux-foundation.org, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 5.11 26/35] bridge: Fix possible races between assigning rx_handler_data and setting IFF_BRIDGE_PORT bit Date: Wed, 12 May 2021 14:01:56 -0400 Message-Id: <20210512180206.664536-26-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210512180206.664536-1-sashal@kernel.org> References: <20210512180206.664536-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Zhang Zhengming [ Upstream commit 59259ff7a81b9eb6213891c6451221e567f8f22f ] There is a crash in the function br_get_link_af_size_filtered, as the port_exists(dev) is true and the rx_handler_data of dev is NULL. But the rx_handler_data of dev is correct saved in vmcore. The oops looks something like: ... pc : br_get_link_af_size_filtered+0x28/0x1c8 [bridge] ... Call trace: br_get_link_af_size_filtered+0x28/0x1c8 [bridge] if_nlmsg_size+0x180/0x1b0 rtnl_calcit.isra.12+0xf8/0x148 rtnetlink_rcv_msg+0x334/0x370 netlink_rcv_skb+0x64/0x130 rtnetlink_rcv+0x28/0x38 netlink_unicast+0x1f0/0x250 netlink_sendmsg+0x310/0x378 sock_sendmsg+0x4c/0x70 __sys_sendto+0x120/0x150 __arm64_sys_sendto+0x30/0x40 el0_svc_common+0x78/0x130 el0_svc_handler+0x38/0x78 el0_svc+0x8/0xc In br_add_if(), we found there is no guarantee that assigning rx_handler_data to dev->rx_handler_data will before setting the IFF_BRIDGE_PORT bit of priv_flags. So there is a possible data competition: CPU 0: CPU 1: (RCU read lock) (RTNL lock) rtnl_calcit() br_add_slave() if_nlmsg_size() br_add_if() br_get_link_af_size_filtered() -> netdev_rx_handler_register ... // The order is not guaranteed ... -> dev->priv_flags |= IFF_BRIDGE_PORT; // The IFF_BRIDGE_PORT bit of priv_flags has been set -> if (br_port_exists(dev)) { // The dev->rx_handler_data has NOT been assigned -> p = br_port_get_rcu(dev); .... -> rcu_assign_pointer(dev->rx_handler_data, rx_handler_data); ... Fix it in br_get_link_af_size_filtered, using br_port_get_check_rcu() and checking the return value. Signed-off-by: Zhang Zhengming Reviewed-by: Zhao Lei Reviewed-by: Wang Xiaogang Suggested-by: Nikolay Aleksandrov Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/bridge/br_netlink.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c index 49700ce0e919..a0a134050b2c 100644 --- a/net/bridge/br_netlink.c +++ b/net/bridge/br_netlink.c @@ -102,8 +102,9 @@ static size_t br_get_link_af_size_filtered(const struct net_device *dev, rcu_read_lock(); if (netif_is_bridge_port(dev)) { - p = br_port_get_rcu(dev); - vg = nbp_vlan_group_rcu(p); + p = br_port_get_check_rcu(dev); + if (p) + vg = nbp_vlan_group_rcu(p); } else if (dev->priv_flags & IFF_EBRIDGE) { br = netdev_priv(dev); vg = br_vlan_group_rcu(br); -- 2.30.2