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=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 66816C2D0CD for ; Wed, 18 Dec 2019 15:15:13 +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 32BC32465E for ; Wed, 18 Dec 2019 15:15:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=crudebyte.com header.i=@crudebyte.com header.b="ah2CfLyX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 32BC32465E Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=crudebyte.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:55564 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ihb2e-0003Es-10 for qemu-devel@archiver.kernel.org; Wed, 18 Dec 2019 10:15:12 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:41668) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from <4866c87cb19f3191b977fc7fbe2857abf1da80b6@lizzy.crudebyte.com>) id 1ihb1F-0001ku-2q for qemu-devel@nongnu.org; Wed, 18 Dec 2019 10:13:46 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from <4866c87cb19f3191b977fc7fbe2857abf1da80b6@lizzy.crudebyte.com>) id 1ihb1D-0006Sx-RI for qemu-devel@nongnu.org; Wed, 18 Dec 2019 10:13:44 -0500 Received: from lizzy.crudebyte.com ([91.194.90.13]:54257) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from <4866c87cb19f3191b977fc7fbe2857abf1da80b6@lizzy.crudebyte.com>) id 1ihb1D-0001Ee-DX for qemu-devel@nongnu.org; Wed, 18 Dec 2019 10:13:43 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=lizzy; h=Subject:Date:Cc:To:From:References:In-Reply-To: Message-Id:Content-Type:Content-Transfer-Encoding:MIME-Version:Content-ID: Content-Description; bh=KBohi6m8+kT0YLSCXjzWFKtZubkOcD4kA+IhcBSo+mw=; b=ah2Cf LyXsVtfD5kaavf/HCnjbAyxDT4DplQ1n7xL6ZK4e4x7ElOm15ExiWi8uhv2LgdmB1XxgrvNGAK5R8 knYy/sJlL48B0U9ZusyF3TzsDq/TZnQP7IevfJP9QCIJNBLGz1S08tbKpDBdZd2TGjFSq/TYz2wIo pYYOCN9QCMh27TwrcfPQEQFik+HxqjW9p4lgamz8xIJE/bEPLbWUMI3nrRpVP8UMEcjnskZlWY1Mo b3iPde73l/ePUs5ftWtVeUpk7rA0tEyeAtKvju9Y9d72SEbPsIycAzyuSxbSr2EOssf3DxRcBcWhA 6yrDdtB9LGmOn3ztqM+d3Arx/bwsw==; Message-Id: <4866c87cb19f3191b977fc7fbe2857abf1da80b6.1576678644.git.qemu_oss@crudebyte.com> In-Reply-To: References: From: Christian Schoenebeck To: qemu-devel@nongnu.org Cc: Greg Kurz Date: Wed, 18 Dec 2019 14:17:59 +0100 Subject: [PATCH v2 2/9] 9pfs: validate count sent by client with T_readdir X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 91.194.90.13 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" A good 9p client sends T_readdir with "count" parameter that's sufficiently smaller than client's initially negotiated msize (maximum message size). We perform a check for that though to avoid the server to be interrupted with a "Failed to encode VirtFS reply type 41" error message by bad clients. Note: we should probably also check for a minimum size of msize during T_version to avoid issues and/or too complicated count/size checks later on in other requests of that client. T_version should submit an msize that's at least as large as the largest request's header size. Signed-off-by: Christian Schoenebeck --- hw/9pfs/9p.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index 520177f40c..30e33b6573 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -2414,6 +2414,7 @@ static void coroutine_fn v9fs_readdir(void *opaque) int32_t count; uint32_t max_count; V9fsPDU *pdu = opaque; + V9fsState *s = pdu->s; retval = pdu_unmarshal(pdu, offset, "dqd", &fid, &initial_offset, &max_count); @@ -2422,6 +2423,13 @@ static void coroutine_fn v9fs_readdir(void *opaque) } trace_v9fs_readdir(pdu->tag, pdu->id, fid, initial_offset, max_count); + if (max_count > s->msize - P9_IOHDRSZ) { + max_count = s->msize - P9_IOHDRSZ; + warn_report_once( + "9p: bad client: T_readdir with count > msize - P9_IOHDRSZ" + ); + } + fidp = get_fid(pdu, fid); if (fidp == NULL) { retval = -EINVAL; -- 2.20.1