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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 40425C43215 for ; Wed, 4 Dec 2019 01:33:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 12F5C206DF for ; Wed, 4 Dec 2019 01:33:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726843AbfLDBdN (ORCPT ); Tue, 3 Dec 2019 20:33:13 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:6744 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726115AbfLDBdM (ORCPT ); Tue, 3 Dec 2019 20:33:12 -0500 Received: from DGGEMS403-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 318A2BB3A126AFFCA833; Wed, 4 Dec 2019 09:33:11 +0800 (CST) Received: from [127.0.0.1] (10.74.191.121) by DGGEMS403-HUB.china.huawei.com (10.3.19.203) with Microsoft SMTP Server id 14.3.439.0; Wed, 4 Dec 2019 09:33:05 +0800 Subject: Re: [PATCH net 2/3] net: hns3: fix a use after free problem in hns3_nic_maybe_stop_tx() To: David Miller CC: , , , , , , References: <1575342535-2981-3-git-send-email-tanhuazhong@huawei.com> <20191202.192840.1366675580449158510.davem@davemloft.net> <138d0858-7240-ff75-a38c-55e10eefc28d@huawei.com> <20191203.115741.976811473066862969.davem@davemloft.net> From: Yunsheng Lin Message-ID: <8901eba5-17a1-bd16-841c-3858475cfb71@huawei.com> Date: Wed, 4 Dec 2019 09:33:05 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: <20191203.115741.976811473066862969.davem@davemloft.net> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.74.191.121] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/12/4 3:57, David Miller wrote: > From: Yunsheng Lin > Date: Tue, 3 Dec 2019 12:22:11 +0800 > >> 2. When skb_copy() returns success, the hns3_nic_maybe_stop_tx() >> returns -EBUSY when there are not no enough space in the ring to >> send the skb to hardware, and hns3_nic_net_xmit() will return >> NETDEV_TX_BUSY to the upper layer, the upper layer will resend the old >> skb later when driver wakes up the queue, but the old skb has been freed >> by the hns3_nic_maybe_stop_tx(). Because when using the skb_copy() to >> linearize a skb, it will return a new linearized skb, and the old skb is >> freed, the upper layer does not have a reference to the new skb and resend >> using the old skb, which casues a use after freed problem. >> >> This patch is trying to fixes the case 2. >> >> Maybe I should mention why hns3_nic_maybe_stop_tx() returns -EBUSY to >> better describe the problem? > > I think it would help understand the code path you are fixing, yes. Will mention that in the next version, thanks. > > . >