From patchwork Thu Jun 11 01:48:55 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wang Hai X-Patchwork-Id: 1307286 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=huawei.com Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 49j6Nn2FG0z9sSJ for ; Thu, 11 Jun 2020 11:54:33 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726500AbgFKBya (ORCPT ); Wed, 10 Jun 2020 21:54:30 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:58088 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726290AbgFKBy3 (ORCPT ); Wed, 10 Jun 2020 21:54:29 -0400 Received: from DGGEMS401-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 4998A452455622F1EEA3; Thu, 11 Jun 2020 09:49:33 +0800 (CST) Received: from huawei.com (10.175.113.133) by DGGEMS401-HUB.china.huawei.com (10.3.19.201) with Microsoft SMTP Server id 14.3.487.0; Thu, 11 Jun 2020 09:49:26 +0800 From: Wang Hai To: , , , CC: , , , Subject: [PATCH] 9p/trans_fd: Fix concurrency del of req_list in p9_fd_cancelled/p9_read_work Date: Thu, 11 Jun 2020 09:48:55 +0800 Message-ID: <20200611014855.60550-1-wanghai38@huawei.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Originating-IP: [10.175.113.133] X-CFilter-Loop: Reflected Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org p9_read_work and p9_fd_cancelled may be called concurrently. Before list_del(&m->rreq->req_list) in p9_read_work is called, the req->req_list may have been deleted in p9_fd_cancelled. We can fix it by setting req->status to REQ_STATUS_FLSHD after list_del(&req->req_list) in p9_fd_cancelled. Before list_del(&req->req_list) in p9_fd_cancelled is called, the req->req_list may have been deleted in p9_read_work. We should return when req->status = REQ_STATUS_RCVD which means we just received a response for oldreq, so we need do nothing in p9_fd_cancelled. Fixes: 60ff779c4abb ("9p: client: remove unused code and any reference to "cancelled" function") Reported-by: Hulk Robot Signed-off-by: Wang Hai Reported-by: syzbot+77a25acfa0382e06ab23@syzkaller.appspotmail.com --- net/9p/trans_fd.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c index f868cf6fba79..a563699629cb 100644 --- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -718,11 +718,18 @@ static int p9_fd_cancelled(struct p9_client *client, struct p9_req_t *req) { p9_debug(P9_DEBUG_TRANS, "client %p req %p\n", client, req); - /* we haven't received a response for oldreq, - * remove it from the list. + /* If req->status == REQ_STATUS_RCVD, it means we just received a + * response for oldreq, we need do nothing here. Else, remove it from + * the list. */ spin_lock(&client->lock); + if (req->status == REQ_STATUS_RCVD) { + spin_unlock(&client->lock); + return 0; + } + list_del(&req->req_list); + req->status = REQ_STATUS_FLSHD; spin_unlock(&client->lock); p9_req_put(req);