From patchwork Thu Dec 17 16:25:20 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Antoine Tenart X-Patchwork-Id: 11980207 X-Patchwork-Delegate: kuba@kernel.org 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=-17.0 required=3.0 tests=BAYES_00,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 12D06C4361B for ; Thu, 17 Dec 2020 16:26:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D2D4F239E4 for ; Thu, 17 Dec 2020 16:26:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728561AbgLQQ0O (ORCPT ); Thu, 17 Dec 2020 11:26:14 -0500 Received: from mail.kernel.org ([198.145.29.99]:33902 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725930AbgLQQ0N (ORCPT ); Thu, 17 Dec 2020 11:26:13 -0500 From: Antoine Tenart Authentication-Results: mail.kernel.org; dkim=permerror (bad message/signature format) To: davem@davemloft.net, kuba@kernel.org Cc: Antoine Tenart , netdev@vger.kernel.org, pabeni@redhat.com Subject: [PATCH net 3/4] net-sysfs: take the rtnl lock when storing xps_rxqs Date: Thu, 17 Dec 2020 17:25:20 +0100 Message-Id: <20201217162521.1134496-4-atenart@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201217162521.1134496-1-atenart@kernel.org> References: <20201217162521.1134496-1-atenart@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org Callers to __netif_set_xps_queue should take the rtnl lock. Failing to do so can lead to race conditions between netdev_set_num_tc and __netif_set_xps_queue, triggering various oops: - __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. 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_rxqs in a concurrent thread. With the right timing an oops is triggered. Fixes: 8af2c06ff4b1 ("net-sysfs: Add interface for Rx queue(s) map per Tx queue") Signed-off-by: Antoine Tenart --- net/core/net-sysfs.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 65886bfbf822..62ca2f2c0ee6 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -1499,10 +1499,17 @@ static ssize_t xps_rxqs_store(struct netdev_queue *queue, const char *buf, return err; } + if (!rtnl_trylock()) { + bitmap_free(mask); + return restart_syscall(); + } + cpus_read_lock(); err = __netif_set_xps_queue(dev, mask, index, true); cpus_read_unlock(); + rtnl_unlock(); + bitmap_free(mask); return err ? : len; }