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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 04CB7C4332B for ; Thu, 21 Jan 2021 14:51:08 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 AC99D238A1 for ; Thu, 21 Jan 2021 14:51:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AC99D238A1 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.72138.129609 (Exim 4.92) (envelope-from ) id 1l2bIZ-0001xp-JP; Thu, 21 Jan 2021 14:50:59 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 72138.129609; Thu, 21 Jan 2021 14:50:59 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1l2bIZ-0001xi-Fy; Thu, 21 Jan 2021 14:50:59 +0000 Received: by outflank-mailman (input) for mailman id 72138; Thu, 21 Jan 2021 14:50:58 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1l2bIY-0001xb-1k for xen-devel@lists.xen.org; Thu, 21 Jan 2021 14:50:58 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id c41b2c8e-b516-49c6-96b3-8373b79d1643; Thu, 21 Jan 2021 14:50:57 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 4E7BAAC9B; Thu, 21 Jan 2021 14:50:56 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: c41b2c8e-b516-49c6-96b3-8373b79d1643 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1611240656; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=A1zyQnVHKyngpdnhGOdZ3lDA4VPKoYgpDy46l1ttDW0=; b=s6SzouoieHKOWij0HM+MS16jCsIvZ19ZJ7E3tKMvw7KQxmdsgDihmQw+gHvBTLwgO+/7+W VpAYRV9rllBPttYHjg6ghVHtKVi6k42SPVLchzYiAofmPkTljCYDouPMvtbb8sBZBZW5rp gvTIWB1gS1ezWkkdJRWsVfn1e3q+qd0= Subject: Re: Xen Security Advisory 360 v1 - IRQ vector leak on x86 To: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= Cc: xen-devel@lists.xen.org, =?UTF-8?Q?Marek_Marczykowski-G=c3=b3recki?= References: <20210121142012.GB1592@mail-itl> <20210121143440.xucstdfws4ymtete@Air-de-Roger> From: Jan Beulich Message-ID: <2d073bc8-418e-2b8d-9ff7-76b932f829b1@suse.com> Date: Thu, 21 Jan 2021 15:50:55 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <20210121143440.xucstdfws4ymtete@Air-de-Roger> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit On 21.01.2021 15:34, Roger Pau Monné wrote: > On Thu, Jan 21, 2021 at 03:20:12PM +0100, Marek Marczykowski-Górecki wrote: >> On Thu, Jan 21, 2021 at 02:10:48PM +0000, Xen.org security team wrote: >>> Xen Security Advisory XSA-360 >>> >>> IRQ vector leak on x86 >>> >>> ISSUE DESCRIPTION >>> ================= >>> >>> A x86 HVM guest with PCI pass through devices can force the allocation >>> of all IDT vectors on the system by rebooting itself with MSI or MSI-X >>> capabilities enabled and entries setup. >> >> (...) >> >>> MITIGATION >>> ========== >>> >>> Not running HVM guests with PCI pass through devices will avoid the >>> vulnerability. Note that even non-malicious guests can trigger this >>> vulnerability as part of normal operation. >> >> Does the 'on_reboot="destroy"' mitigate the issue too? Or on_soft_reset? > > Kind of. Note you will still leak the in use vectors when the guest is > destroyed, but that would prevent the guest from entering a reboot > loop and exhausting all vectors on the system unless the admin starts > it again. > > In that case I think the premise of a guest 'rebooting itself' doesn't > apply anymore, since the guest won't be able to perform such > operation. And how exactly would an admin tell a guest from rebooting for fair reasons from one rebooting for malicious reasons? To me, setting 'on_reboot="destroy"' would imply there's then some other mechanism to restart the guest (possibly with some delay), or else a reboot attempt by this guest would effectively be a DoS to its users. Jan