From patchwork Wed Dec 23 21:23:20 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Antoine Tenart X-Patchwork-Id: 351765 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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham 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 EF6FBC433DB for ; Wed, 23 Dec 2020 21:24:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A4ADD2246B for ; Wed, 23 Dec 2020 21:24:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729186AbgLWVYJ (ORCPT ); Wed, 23 Dec 2020 16:24:09 -0500 Received: from mail.kernel.org ([198.145.29.99]:50970 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729094AbgLWVYJ (ORCPT ); Wed, 23 Dec 2020 16:24:09 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 675A32246B; Wed, 23 Dec 2020 21:23:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1608758609; bh=Qv7BNaQBGigmchrOczr/Unmy93zZ29j4XMAjksBoIWc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=am+ogcDW/UnuyA2x0N8ww9ObN6VNHgWVd9xGlkEEPzkmbXrHpsXxF7rTvRzkx2mUn J89ULD70k68nyRACwA2XVerrEWVDTmXu91UOPPecKMoySKSh1wiQytQR77S/IOTPET 3eq6acPbrBPG6j9+3fWIyrl1uBrao7amCpXJKUk59QCcg3OPLBkkpk0l4KLC+gJRdd V3lDuQSBkCtz1sQ15K8fOE9tb/a1Qn7Lrly58r/ZY+yMQ7Rus7es/eOTCI4p5Zj+wU 59vFUx88vvVNuB97b09csQ0jMKrxgAvh35+FR+rJVSspQNF9feH//i0Hu9HcEncvAL pZkLv02J2AX3Q== From: Antoine Tenart To: davem@davemloft.net, kuba@kernel.org, alexander.duyck@gmail.com Cc: Antoine Tenart , netdev@vger.kernel.org, pabeni@redhat.com Subject: [PATCH net v3 1/4] net-sysfs: take the rtnl lock when storing xps_cpus Date: Wed, 23 Dec 2020 22:23:20 +0100 Message-Id: <20201223212323.3603139-2-atenart@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201223212323.3603139-1-atenart@kernel.org> References: <20201223212323.3603139-1-atenart@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Two race conditions can be triggered when storing xps cpus, resulting in various oops and invalid memory accesses: 1. Calling netdev_set_num_tc while netif_set_xps_queue: - netif_set_xps_queue uses dev->tc_num as one of the parameters to compute the size of new_dev_maps when allocating it. dev->tc_num is also used to access the map, and the compiler may generate code to retrieve this field multiple times in the function. - netdev_set_num_tc sets dev->tc_num. If new_dev_maps is allocated using dev->tc_num and then dev->tc_num is set to a higher value through netdev_set_num_tc, later accesses to new_dev_maps in netif_set_xps_queue could lead to accessing memory outside of new_dev_maps; triggering an oops. 2. Calling netif_set_xps_queue while netdev_set_num_tc is running: 2.1. netdev_set_num_tc starts by resetting the xps queues, dev->tc_num isn't updated yet. 2.2. netif_set_xps_queue is called, setting up the map with the *old* dev->num_tc. 2.3. netdev_set_num_tc updates dev->tc_num. 2.4. Later accesses to the map lead to out of bound accesses and oops. A similar issue can be found with netdev_reset_tc. One way of triggering this is to set an iface up (for which the driver uses netdev_set_num_tc in the open path, such as bnx2x) and writing to xps_cpus in a concurrent thread. With the right timing an oops is triggered. Both issues have the same fix: netif_set_xps_queue, netdev_set_num_tc and netdev_reset_tc should be mutually exclusive. We do that by taking the rtnl lock in xps_cpus_store. Fixes: 184c449f91fe ("net: Add support for XPS with QoS via traffic classes") Signed-off-by: Antoine Tenart --- net/core/net-sysfs.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 999b70c59761..7cc15dec1717 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -1396,7 +1396,13 @@ static ssize_t xps_cpus_store(struct netdev_queue *queue, return err; } + if (!rtnl_trylock()) { + free_cpumask_var(mask); + return restart_syscall(); + } + err = netif_set_xps_queue(dev, mask, index); + rtnl_unlock(); free_cpumask_var(mask);