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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 3F76FECDE5F for ; Tue, 24 Jul 2018 01:40:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C0EDB20874 for ; Tue, 24 Jul 2018 01:40:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C0EDB20874 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388339AbeGXCoK (ORCPT ); Mon, 23 Jul 2018 22:44:10 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:34172 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2388272AbeGXCoJ (ORCPT ); Mon, 23 Jul 2018 22:44:09 -0400 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 24723798E406C; Tue, 24 Jul 2018 09:40:08 +0800 (CST) Received: from [127.0.0.1] (10.177.16.168) by DGGEMS402-HUB.china.huawei.com (10.3.19.202) with Microsoft SMTP Server id 14.3.382.0; Tue, 24 Jul 2018 09:40:05 +0800 Subject: Re: [PATCH] net/p9/trans_fd.c: fix double list_del() To: Tomas Bortoli , , , References: <20180723121902.20201-1-tomasbortoli@gmail.com> CC: , , , , , From: jiangyiwen Message-ID: <5B568374.9010507@huawei.com> Date: Tue, 24 Jul 2018 09:40:04 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <20180723121902.20201-1-tomasbortoli@gmail.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.16.168] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018/7/23 20:19, Tomas Bortoli wrote: > A double list_del(&req->req_list) is possible in p9_fd_cancel() as > shown by Syzbot. To prevent it we have to ensure that we have the > client->lock when deleting the list. Furthermore, we have to update > the status of the request before releasing the lock, to prevent the > race. > > Signed-off-by: Tomas Bortoli > Reported-by: syzbot+735d926e9d1317c3310c@syzkaller.appspotmail.com > --- > net/9p/trans_fd.c | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) > > diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c > index a64b01c56e30..370c6c69a05c 100644 > --- a/net/9p/trans_fd.c > +++ b/net/9p/trans_fd.c > @@ -199,15 +199,14 @@ static void p9_mux_poll_stop(struct p9_conn *m) > static void p9_conn_cancel(struct p9_conn *m, int err) > { > struct p9_req_t *req, *rtmp; > - unsigned long flags; > LIST_HEAD(cancel_list); > > p9_debug(P9_DEBUG_ERROR, "mux %p err %d\n", m, err); > > - spin_lock_irqsave(&m->client->lock, flags); > + spin_lock(&m->client->lock); > > if (m->err) { > - spin_unlock_irqrestore(&m->client->lock, flags); > + spin_unlock(&m->client->lock); > return; > } > > @@ -219,7 +218,6 @@ static void p9_conn_cancel(struct p9_conn *m, int err) > list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) { > list_move(&req->req_list, &cancel_list); > } > - spin_unlock_irqrestore(&m->client->lock, flags); > > list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) { > p9_debug(P9_DEBUG_ERROR, "call back req %p\n", req); > @@ -228,6 +226,7 @@ static void p9_conn_cancel(struct p9_conn *m, int err) > req->t_err = err; > p9_client_cb(m->client, req, REQ_STATUS_ERROR); > } > + spin_unlock(&m->client->lock); If you want to expand the ranges of client->lock, the cancel_list will not be necessary, you can optimize this code. Thanks, Yiwen. > } > > static __poll_t > @@ -370,12 +369,12 @@ static void p9_read_work(struct work_struct *work) > if (m->req->status != REQ_STATUS_ERROR) > status = REQ_STATUS_RCVD; > list_del(&m->req->req_list); > - spin_unlock(&m->client->lock); > p9_client_cb(m->client, m->req, status); > m->rc.sdata = NULL; > m->rc.offset = 0; > m->rc.capacity = 0; > m->req = NULL; > + spin_unlock(&m->client->lock); > } > > end_clear: >