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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 2FA2AC433FF for ; Tue, 30 Jul 2019 00:34:47 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0119E2070B for ; Tue, 30 Jul 2019 00:34:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0119E2070B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:57196 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hsG6I-00087Q-9K for qemu-devel@archiver.kernel.org; Mon, 29 Jul 2019 20:34:46 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:59020) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hsG5r-0007dd-2W for qemu-devel@nongnu.org; Mon, 29 Jul 2019 20:34:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hsG5p-0006T5-5g for qemu-devel@nongnu.org; Mon, 29 Jul 2019 20:34:19 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:43864 helo=huawei.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hsG5o-0006R0-Jc for qemu-devel@nongnu.org; Mon, 29 Jul 2019 20:34:17 -0400 Received: from DGGEMS408-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 8F55EEA39494D70861EB; Tue, 30 Jul 2019 08:34:12 +0800 (CST) Received: from [10.177.253.249] (10.177.253.249) by smtp.huawei.com (10.3.19.208) with Microsoft SMTP Server id 14.3.439.0; Tue, 30 Jul 2019 08:34:02 +0800 To: Stefan Hajnoczi References: <20190726091103.23503-1-stefanha@redhat.com> <20190726091103.23503-3-stefanha@redhat.com> <20190729154118.GA21560@stefanha-x1.localdomain> From: piaojun Message-ID: <5D3F9078.2070607@huawei.com> Date: Tue, 30 Jul 2019 08:34:00 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <20190729154118.GA21560@stefanha-x1.localdomain> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.253.249] X-CFilter-Loop: Reflected X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 45.249.212.35 Subject: Re: [Qemu-devel] [Virtio-fs] [PATCH 2/5] virtiofsd: prevent lo_lookup() NULL pointer dereference X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: virtio-fs@redhat.com, piaojun@huawei.com, qemu-devel@nongnu.org, Stefan Hajnoczi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 2019/7/29 23:41, Stefan Hajnoczi wrote: > On Mon, Jul 29, 2019 at 08:35:36PM +0800, piaojun wrote: >> Hi Stefan, >> >> On 2019/7/26 17:11, Stefan Hajnoczi wrote: >>> Most lo_do_lookup() have already checked that the parent inode exists. >>> lo_lookup() hasn't and can therefore hit a NULL pointer dereference when >>> lo_inode(req, parent) returns NULL. >>> >>> Signed-off-by: Stefan Hajnoczi >>> --- >>> contrib/virtiofsd/passthrough_ll.c | 4 ++++ >>> 1 file changed, 4 insertions(+) >>> >>> diff --git a/contrib/virtiofsd/passthrough_ll.c b/contrib/virtiofsd/passthrough_ll.c >>> index 9ae1381618..277a17fc03 100644 >>> --- a/contrib/virtiofsd/passthrough_ll.c >>> +++ b/contrib/virtiofsd/passthrough_ll.c >>> @@ -766,6 +766,10 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name, >>> struct lo_data *lo = lo_data(req); >>> struct lo_inode *inode, *dir = lo_inode(req, parent); >>> >>> + if (!dir) { >>> + return EBADF; >>> + } >>> + >> >> I worry about that dir will be released or set NULL just after NULL >> checking. Or could we use some lock to prevent the simultaneity? > > Yes, I agree. I haven't audited lo_inode yet, but it needs a refcount > and/or lock to ensure accesses are safe. I'll do that and other things > in a separate patch series. > > Stefan OK, that sounds good. Jun >