From patchwork Fri Jun 12 09:08:33 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wang Hai X-Patchwork-Id: 217804 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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 AEA1FC433E0 for ; Fri, 12 Jun 2020 09:09:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 832D4207D8 for ; Fri, 12 Jun 2020 09:09:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726462AbgFLJJV (ORCPT ); Fri, 12 Jun 2020 05:09:21 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:33556 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726302AbgFLJJT (ORCPT ); Fri, 12 Jun 2020 05:09:19 -0400 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 77CE3E1C964E39C45171; Fri, 12 Jun 2020 17:09:16 +0800 (CST) Received: from huawei.com (10.175.113.133) by DGGEMS409-HUB.china.huawei.com (10.3.19.209) with Microsoft SMTP Server id 14.3.487.0; Fri, 12 Jun 2020 17:09:05 +0800 From: Wang Hai To: , , , CC: , , , Subject: [PATCH v2] 9p/trans_fd: Fix concurrency del of req_list in p9_fd_cancelled/p9_read_work Date: Fri, 12 Jun 2020 17:08:33 +0800 Message-ID: <20200612090833.36149-1-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. In some cases, req->req_list may be deleted by both p9_read_work and p9_fd_cancelled. We can fix it by ignoring replies associated with a cancelled request and ignoring cancelled request if message has been received before lock. Fixes: 60ff779c4abb ("9p: client: remove unused code and any reference to "cancelled" function") Reported-by: syzbot+77a25acfa0382e06ab23@syzkaller.appspotmail.com Signed-off-by: Wang Hai --- v1->v2: 1. Add ignoring replies associated with a cancelled request. 2. Improved some descriptions suggested by Dominique. net/9p/trans_fd.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c index 13cd683a658a..3f67803123be 100644 --- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -362,6 +362,10 @@ static void p9_read_work(struct work_struct *work) if (m->rreq->status == REQ_STATUS_SENT) { list_del(&m->rreq->req_list); p9_client_cb(m->client, m->rreq, REQ_STATUS_RCVD); + } else if (m->rreq->status == REQ_STATUS_FLSHD) { + /* Ignore replies associated with a cancelled request. */ + p9_debug(P9_DEBUG_TRANS, + "Ignore replies associated with a cancelled request\n"); } else { spin_unlock(&m->client->lock); p9_debug(P9_DEBUG_ERROR, @@ -703,11 +707,20 @@ 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); + spin_lock(&client->lock); + /* Ignore cancelled request if message has been received + * before lock. + */ + if (req->status == REQ_STATUS_RCVD) { + spin_unlock(&client->lock); + return 0; + } + /* we haven't received a response for oldreq, * remove it from the list. */ - spin_lock(&client->lock); list_del(&req->req_list); + req->status = REQ_STATUS_FLSHD; spin_unlock(&client->lock); p9_req_put(req);