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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 9516CC76192 for ; Tue, 16 Jul 2019 11:26:03 +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 70DA4205C9 for ; Tue, 16 Jul 2019 11:26:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 70DA4205C9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:47360 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hnLas-0000zB-BT for qemu-devel@archiver.kernel.org; Tue, 16 Jul 2019 07:26:02 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:37606) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hnLah-0000XA-Pw for qemu-devel@nongnu.org; Tue, 16 Jul 2019 07:25:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hnLag-00019O-Rb for qemu-devel@nongnu.org; Tue, 16 Jul 2019 07:25:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55914) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hnLae-00016p-RM; Tue, 16 Jul 2019 07:25:48 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E5BF283F42; Tue, 16 Jul 2019 11:25:47 +0000 (UTC) Received: from linux.fritz.box (ovpn-117-24.ams2.redhat.com [10.36.117.24]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 04F99600C1; Tue, 16 Jul 2019 11:25:36 +0000 (UTC) Date: Tue, 16 Jul 2019 13:25:35 +0200 From: Kevin Wolf To: Alexander Popov Message-ID: <20190716112535.GB7297@linux.fritz.box> References: <1562335669-10127-1-git-send-email-alex.popov@linux.com> <0bce1e99-fb98-6354-9426-391a3e9363f1@linux.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0bce1e99-fb98-6354-9426-391a3e9363f1@linux.com> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Tue, 16 Jul 2019 11:25:48 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [Qemu-block] [QEMU-SECURITY] ide: fix assertion in ide_dma_cb() to prevent qemu DoS from quest 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: sstabellini@kernel.org, pmatouse@redhat.com, mdroth@linux.vnet.ibm.com, qemu-block@nongnu.org, mst@redhat.com, qemu-devel@nongnu.org, qemu-stable@nongnu.org, John Snow , pjp@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 15.07.2019 um 13:24 hat Alexander Popov geschrieben: > On 05.07.2019 17:07, Alexander Popov wrote: > > This assertion was introduced in the commit a718978ed58a in July 2015. > > It implies that the size of successful DMA transfers handled in > > ide_dma_cb() should be multiple of 512 (the size of a sector). > > > > But guest systems can initiate DMA transfers that don't fit this > > requirement. Let's improve the assertion to prevent qemu DoS from quests. > > Hello! > > Just a friendly ping. > > Could you have a look at this patch? John, I think this is for you. I haven't reviewed this yet, but if we put an assertion there that the request is aligned, we probably rely on this fact somewhere in the code. So I suspect that just changing the assertion without changing other code, too, might not be enough. Kevin