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=-5.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 6CF19C49ED6 for ; Wed, 11 Sep 2019 12:33:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 43E332082C for ; Wed, 11 Sep 2019 12:33:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568205201; bh=eN1N5vPP2BYE5r+wilFLEutQv6wNUw7Z0cM/4TJqqQ0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=mwxUvgASTvgMyUEUjBKukWK2ZNIzsSW8svhGEjFR0uQB2JQGBed3TbM5qG6uEBQGm AlaqH/wXCvR0paPJHYw9xczhnsS8QpoLsj2LkiHrYn3tbW8mcP80JGKyw+Giq5jv5d WjINIEmxkSBjiPaJVDDla4ZNxNYJkAqnFrx+4+3Y= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727809AbfIKMdS (ORCPT ); Wed, 11 Sep 2019 08:33:18 -0400 Received: from mx2.suse.de ([195.135.220.15]:40740 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726198AbfIKMdS (ORCPT ); Wed, 11 Sep 2019 08:33:18 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id A71A0AC3E; Wed, 11 Sep 2019 12:33:16 +0000 (UTC) Date: Wed, 11 Sep 2019 14:33:16 +0200 From: Michal Hocko To: "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, Jason Wang , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org Subject: Re: [PATCH v2] vhost: block speculation of translated descriptors Message-ID: <20190911123316.GX4023@dhcp22.suse.cz> References: <20190911120908.28410-1-mst@redhat.com> <20190911121628.GT4023@dhcp22.suse.cz> <20190911082236-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190911082236-mutt-send-email-mst@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed 11-09-19 08:25:03, Michael S. Tsirkin wrote: > On Wed, Sep 11, 2019 at 02:16:28PM +0200, Michal Hocko wrote: > > On Wed 11-09-19 08:10:00, Michael S. Tsirkin wrote: > > > iovec addresses coming from vhost are assumed to be > > > pre-validated, but in fact can be speculated to a value > > > out of range. > > > > > > Userspace address are later validated with array_index_nospec so we can > > > be sure kernel info does not leak through these addresses, but vhost > > > must also not leak userspace info outside the allowed memory table to > > > guests. > > > > > > Following the defence in depth principle, make sure > > > the address is not validated out of node range. > > > > > > Signed-off-by: Michael S. Tsirkin > > > Acked-by: Jason Wang > > > Tested-by: Jason Wang > > > > no need to mark fo stable? Other spectre fixes tend to be backported > > even when the security implications are not really clear. The risk > > should be low and better to be covered in case. > > This is not really a fix - more a defence in depth thing, > quite similar to e.g. commit b3bbfb3fb5d25776b8e3f361d2eedaabb0b496cd > x86: Introduce __uaccess_begin_nospec() and uaccess_try_nospec > in scope. > > That one doesn't seem to be tagged for stable. Was it queued > there in practice? not marked for stable but it went in. At least to 4.4. -- Michal Hocko SUSE Labs