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 44A91C5CFE7 for ; Wed, 11 Jul 2018 02:27:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 029A9208EC for ; Wed, 11 Jul 2018 02:27:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 029A9208EC 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 S1732685AbeGKC3h (ORCPT ); Tue, 10 Jul 2018 22:29:37 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:9219 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1732524AbeGKC3g (ORCPT ); Tue, 10 Jul 2018 22:29:36 -0400 Received: from DGGEMS408-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 3C3F5D0F8AA70; Wed, 11 Jul 2018 10:27:25 +0800 (CST) Received: from [127.0.0.1] (10.177.16.168) by DGGEMS408-HUB.china.huawei.com (10.3.19.208) with Microsoft SMTP Server id 14.3.382.0; Wed, 11 Jul 2018 10:27:25 +0800 Subject: Re: [V9fs-developer] [PATCH] p9_check_errors() validate PDU length To: Tomas Bortoli , , , , Andrew Morton References: <20180709224323.20597-1-tomasbortoli@gmail.com> CC: , , , , From: jiangyiwen Message-ID: <5B456B0B.6020301@huawei.com> Date: Wed, 11 Jul 2018 10:27:23 +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: <20180709224323.20597-1-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 2018/7/10 6:43, Tomas Bortoli wrote: > p9_check_errors() does not validate the size of the PDU read > in p9_parse_header(). Any size can be passed, provoking out-of-bound reads. > > Signed-off-by: Tomas Bortoli > Reported-by: syzbot+65c6b72f284a39d416b4@syzkaller.appspotmail.com > --- > As suggested by Dominique: > https://lkml.org/lkml/2018/7/9/688 > Such check is not enough as it will prevent to read more than how it has > been allocated but it won't prevent to read more than how it has been read > So this patch will require some more changes to prevent bad sizes. > > net/9p/client.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/net/9p/client.c b/net/9p/client.c > index 40f7c47f2f74..5b161b576b8a 100644 > --- a/net/9p/client.c > +++ b/net/9p/client.c > @@ -520,10 +520,13 @@ EXPORT_SYMBOL(p9_parse_header); > static int p9_check_errors(struct p9_client *c, struct p9_req_t *req) > { > int8_t type; > + int32_t size; > int err; > int ecode; > > - err = p9_parse_header(req->rc, NULL, &type, NULL, 0); > + err = p9_parse_header(req->rc, &size, &type, NULL, 0); > + if (size > req->rc->capacity) > + return -EINVAL; Yes, currently 9p client is lacking of properly check for data from server. Maybe we should have a bigger patch to solve this problem. > /* > * dump the response from server > * This should be after check errors which poplulate pdu_fcall. >