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=-6.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 autolearn=no 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 E6463C433E1 for ; Tue, 25 Aug 2020 08:26:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C07F32071E for ; Tue, 25 Aug 2020 08:26:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="IWhxqaKE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729028AbgHYI0x (ORCPT ); Tue, 25 Aug 2020 04:26:53 -0400 Received: from aserp2120.oracle.com ([141.146.126.78]:59030 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728133AbgHYI0w (ORCPT ); Tue, 25 Aug 2020 04:26:52 -0400 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 07P8Nj5N094460; Tue, 25 Aug 2020 08:26:45 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2020-01-29; bh=PjJiapN6S66feKThBGgHeW3S/yTm+iArd2Yb3om4uTQ=; b=IWhxqaKEgAMvOc0eRh9Me6+srFa6pgVwAQBs+5tTjzsbBR1vUPFiNpwV9jyMBi7bG8j8 Zi21mO8dnlXJXE8nWVW5GuPXKv801vByqFbVmyXi35epO2ycmxtP5AbRYLS9IPNxwlHj D7WRNPH/f1Cm1hSHQfichHYDN88oFyl6I5t3MrF1hcnJEOnVYtU2u0uoVj+40TWEbJK8 6DEd9WQunod9uIU9jF/mU9/DXPHRdWZCyGvuGwFBW+ob1WtsCzEoeRC6SP1575H9FfOo ilPvR+Ie9Fw7l1rQ8aaDo+K9Z03TVv8WFyH+1StjR8OsFunQOoPchiQh5uhzzajEQoan qA== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by aserp2120.oracle.com with ESMTP id 333dbrs038-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 25 Aug 2020 08:26:45 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 07P8KBIs022599; Tue, 25 Aug 2020 08:24:45 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserp3020.oracle.com with ESMTP id 333ru6xhrq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 25 Aug 2020 08:24:45 +0000 Received: from abhmp0015.oracle.com (abhmp0015.oracle.com [141.146.116.21]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 07P8Ohnj026831; Tue, 25 Aug 2020 08:24:44 GMT Received: from kadam (/41.57.98.10) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 25 Aug 2020 01:24:43 -0700 Date: Tue, 25 Aug 2020 11:24:37 +0300 From: Dan Carpenter To: "Jason A. Donenfeld" Cc: netdev@vger.kernel.org, "David S . Miller" Subject: Re: [PATCH net] net: read dev->needs_free_netdev before potentially freeing dev Message-ID: <20200825082437.GQ5493@kadam> References: <20200824141519.GA223008@mwanda> <20200824200650.21982-1-Jason@zx2c4.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200824200650.21982-1-Jason@zx2c4.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9723 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 phishscore=0 bulkscore=0 suspectscore=2 spamscore=0 mlxscore=0 adultscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008250064 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9723 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 clxscore=1015 priorityscore=1501 impostorscore=0 phishscore=0 malwarescore=0 mlxlogscore=999 spamscore=0 mlxscore=0 lowpriorityscore=0 suspectscore=2 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008250065 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Aug 24, 2020 at 10:06:50PM +0200, Jason A. Donenfeld wrote: > If dev->needs_free_netdev is true, it means that netdev_run_todo should > call free_netdev(dev) after it calls dev->priv_destructor. If > dev->needs_free_netdev is false, then it means that either > dev->priv_destructor is taking care of calling free_netdev(dev), or > something else, elsewhere, is doing that. In this case, branching on > "if (dev->needs_free_netdev)" after calling dev->priv_destructor is a > potential UaF. This patch fixes the issue by reading > dev->needs_free_netdev before calling dev->priv_destructor. > No, I misread the code. Sorry. This patch is not required. We can use "dev" up to the end of the function where we do: /* Free network device */ kobject_put(&dev->dev.kobj); That's where the final reference is released. regards, dan carpenter