From patchwork Tue Sep 1 00:55:18 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yunsheng Lin X-Patchwork-Id: 261713 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=-13.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, 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 9B6FCC433E6 for ; Tue, 1 Sep 2020 00:59:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 80D6A208A9 for ; Tue, 1 Sep 2020 00:59:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726249AbgIAA7D (ORCPT ); Mon, 31 Aug 2020 20:59:03 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:44932 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725872AbgIAA7C (ORCPT ); Mon, 31 Aug 2020 20:59:02 -0400 Received: from DGGEMS407-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 740091D2606C0AE80B4C; Tue, 1 Sep 2020 08:58:59 +0800 (CST) Received: from localhost.localdomain (10.69.192.58) by DGGEMS407-HUB.china.huawei.com (10.3.19.207) with Microsoft SMTP Server id 14.3.487.0; Tue, 1 Sep 2020 08:58:51 +0800 From: Yunsheng Lin To: , , , , CC: , , Subject: [PATCH net-next] net: sch_generic: aviod concurrent reset and enqueue op for lockless qdisc Date: Tue, 1 Sep 2020 08:55:18 +0800 Message-ID: <1598921718-79505-1-git-send-email-linyunsheng@huawei.com> X-Mailer: git-send-email 2.8.1 MIME-Version: 1.0 X-Originating-IP: [10.69.192.58] X-CFilter-Loop: Reflected Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Currently there is concurrent reset and enqueue operation for the same lockless qdisc when there is no lock to synchronize the q->enqueue() in __dev_xmit_skb() with the qdisc reset operation in qdisc_deactivate() called by dev_deactivate_queue(), which may cause out-of-bounds access for priv->ring[] in hns3 driver if user has requested a smaller queue num when __dev_xmit_skb() still enqueue a skb with a larger queue_mapping after the corresponding qdisc is reset, and call hns3_nic_net_xmit() with that skb later. Avoid the above concurrent op by calling synchronize_rcu_tasks() after assigning new qdisc to dev_queue->qdisc and before calling qdisc_deactivate() to make sure skb with larger queue_mapping enqueued to old qdisc will always be reset when qdisc_deactivate() is called. Signed-off-by: Yunsheng Lin Reported-by: kernel test robot --- net/sched/sch_generic.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index 265a61d..6e42237 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -1160,8 +1160,13 @@ static void dev_deactivate_queue(struct net_device *dev, qdisc = rtnl_dereference(dev_queue->qdisc); if (qdisc) { - qdisc_deactivate(qdisc); rcu_assign_pointer(dev_queue->qdisc, qdisc_default); + + /* Make sure lockless qdisc enqueuing is done with the + * old qdisc in __dev_xmit_skb(). + */ + synchronize_rcu_tasks(); + qdisc_deactivate(qdisc); } }