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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 77392C43381 for ; Wed, 6 Mar 2019 18:53:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 49A6B2063F for ; Wed, 6 Mar 2019 18:53:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727907AbfCFSxs (ORCPT ); Wed, 6 Mar 2019 13:53:48 -0500 Received: from shards.monkeyblade.net ([23.128.96.9]:39196 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726512AbfCFSxs (ORCPT ); Wed, 6 Mar 2019 13:53:48 -0500 Received: from localhost (unknown [IPv6:2601:601:9f80:35cd::d71]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 3E0C5144FEB6E; Wed, 6 Mar 2019 10:53:47 -0800 (PST) Date: Wed, 06 Mar 2019 10:53:46 -0800 (PST) Message-Id: <20190306.105346.2043508562178833304.davem@davemloft.net> To: vladbu@mellanox.com Cc: netdev@vger.kernel.org, jhs@mojatatu.com, xiyou.wangcong@gmail.com, jiri@resnulli.us, roid@mellanox.com Subject: Re: [PATCH net] net: sched: flower: insert new filter to idr after setting its mask From: David Miller In-Reply-To: <20190306142212.1519-1-vladbu@mellanox.com> References: <20190306142212.1519-1-vladbu@mellanox.com> X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Wed, 06 Mar 2019 10:53:47 -0800 (PST) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Vlad Buslov Date: Wed, 6 Mar 2019 16:22:12 +0200 > When adding new filter to flower classifier, fl_change() inserts it to > handle_idr before initializing filter extensions and assigning it a mask. > Normally this ordering doesn't matter because all flower classifier ops > callbacks assume rtnl lock protection. However, when filter has an action > that doesn't have its kernel module loaded, rtnl lock is released before > call to request_module(). During this time the filter can be accessed bu > concurrent task before its initialization is completed, which can lead to a > crash. > > Example case of NULL pointer dereference in concurrent dump: ... > Extension initialization and mask assignment don't depend on fnew->handle > that is allocated by idr_alloc_u32(). Move idr allocation code after action > creation and mask assignment in fl_change() to prevent concurrent access > to not fully initialized filter when rtnl lock is released to load action > module. > > Fixes: 01683a146999 ("net: sched: refactor flower walk to iterate over idr") > Signed-off-by: Vlad Buslov > Reviewed-by: Roi Dayan Applied and queued up for -stable.