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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29B6CC433EF for ; Thu, 24 Mar 2022 03:18:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347934AbiCXDTm (ORCPT ); Wed, 23 Mar 2022 23:19:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59032 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241880AbiCXDTh (ORCPT ); Wed, 23 Mar 2022 23:19:37 -0400 Received: from codeconstruct.com.au (pi.codeconstruct.com.au [203.29.241.158]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7C604DD6; Wed, 23 Mar 2022 20:18:04 -0700 (PDT) Received: from [192.168.12.102] (unknown [159.196.94.94]) by mail.codeconstruct.com.au (Postfix) with ESMTPSA id 255C82029E; Thu, 24 Mar 2022 11:17:56 +0800 (AWST) Message-ID: <61ac01e70c293b7e0d378436f7617daaad552fcf.camel@codeconstruct.com.au> Subject: Re: [PATCH v0] mctp: fix netdev reference bug From: Matt Johnston To: Lin Ma , jk@codeconstruct.com.au, davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Date: Thu, 24 Mar 2022 11:17:56 +0800 In-Reply-To: <20220324023904.7173-1-linma@zju.edu.cn> References: <20220324023904.7173-1-linma@zju.edu.cn> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.40.4-1ubuntu2 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Lin Ma, On Thu, 2022-03-24 at 10:39 +0800, Lin Ma wrote: > In extended addressing mode, function mctp_local_output() fetch netdev > through dev_get_by_index_rcu, which won't increase netdev's reference > counter. Hence, the reference may underflow when mctp_local_output calls > dev_put(), results in possible use after free. > > This patch adds dev_hold() to fix the reference bug. This was already fixed in net-next to increment the refcount in __mctp_dev_get() and use mctp_dev_put(). dc121c008491 ("mctp: make __mctp_dev_get() take a refcount hold") e297db3eadd7 ("mctp: Fix incorrect netdev unref for extended addr") Thanks, Matt