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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 8871FC4CEC7 for ; Sat, 14 Sep 2019 08:08:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5ED0A2089C for ; Sat, 14 Sep 2019 08:08:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568448524; bh=XneftSq4r8FsDIABRdbMyQuUcgxfolt9wszU1cxTwrk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=O+DoNFGYPXKZ/vKrdU0Begagj9xFiJmREjxpGkxPFbgirbKFqYHMViwAuitsFFUT5 09VcEXUOgLZr1qBPen+C11vB4m61seHYt2eU9A9UzbYbpEovBljzejCFOHicTh0bo5 amA/TO3ljjOCcMAO0r4Nx9JTVXicIS+W0rieKgwE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727450AbfINIIn (ORCPT ); Sat, 14 Sep 2019 04:08:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:39834 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727171AbfINIIn (ORCPT ); Sat, 14 Sep 2019 04:08:43 -0400 Received: from localhost (unknown [84.241.204.167]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5F89D20692; Sat, 14 Sep 2019 08:08:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568448522; bh=XneftSq4r8FsDIABRdbMyQuUcgxfolt9wszU1cxTwrk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=S4n0qcTkKSEctugVIlNcglPeZA5zGOE794fhpYCoUIdTHDBaMglCy8K7mnTA4csSE BcSctTGUmqUY7hMfpaeoXRnrdozjFxO5ZZ3dtfEzbwyZJjYCMnDMS3temWAKiVvYa+ WQQTLimwmolqZmNSFrjIkO06DOktumnxZMdGVx8A= Date: Sat, 14 Sep 2019 09:08:36 +0100 From: Greg Kroah-Hartman To: Stefan Lippers-Hollmann Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, "Michael S. Tsirkin" , Jason Wang Subject: Re: [PATCH 5.2 36/37] vhost: block speculation of translated descriptors Message-ID: <20190914080836.GB522114@kroah.com> References: <20190913130510.727515099@linuxfoundation.org> <20190913130522.155505270@linuxfoundation.org> <20190914025411.3016e3d9@mir> <20190914055050.GA489003@kroah.com> <20190914091548.230a63de@mir> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190914091548.230a63de@mir> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Sep 14, 2019 at 09:15:48AM +0200, Stefan Lippers-Hollmann wrote: > Hi > > On 2019-09-14, Greg Kroah-Hartman wrote: > > On Sat, Sep 14, 2019 at 02:54:11AM +0200, Stefan Lippers-Hollmann wrote: > > > On 2019-09-13, Greg Kroah-Hartman wrote: > > > > From: Michael S. Tsirkin > > > > > > > > commit a89db445fbd7f1f8457b03759aa7343fa530ef6b upstream. > > > > > > > > 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. > [...] > > Do you have the same problem with Linus's tree right now? > > Actually, yes I do (I had not tested i386 for 5.3~ within the last ~2 > weeks, only amd64). Very similar kernel config, same compiler versions > but built in a slightly different environment (built directly on the bare > iron, in a amd64 multilib userspace, rather than a pure-i386 chroot on an > amd64 kernel). > > $ git describe > v5.3-rc8-36-ga7f89616b737 > > $ LANG= make ARCH=x86 -j1 bzImage modules > CALL scripts/checksyscalls.sh > CALL scripts/atomic/check-atomics.sh > CHK include/generated/compile.h > CHK kernel/kheaders_data.tar.xz > CC [M] drivers/vhost/vhost.o > In file included from ./include/linux/export.h:45, > from ./include/linux/linkage.h:7, > from ./include/linux/kernel.h:8, > from ./include/linux/list.h:9, > from ./include/linux/wait.h:7, > from ./include/linux/eventfd.h:13, > from drivers/vhost/vhost.c:13: > drivers/vhost/vhost.c: In function 'translate_desc': > ./include/linux/compiler.h:350:38: error: call to '__compiletime_assert_2076' declared with attribute error: BUILD_BUG_ON failed: sizeof(_s) > sizeof(long) > 350 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > | ^ > ./include/linux/compiler.h:331:4: note: in definition of macro '__compiletime_assert' > 331 | prefix ## suffix(); \ > | ^~~~~~ > ./include/linux/compiler.h:350:2: note: in expansion of macro '_compiletime_assert' > 350 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > | ^~~~~~~~~~~~~~~~~~~ > ./include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert' > 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) > | ^~~~~~~~~~~~~~~~~~ > ./include/linux/build_bug.h:50:2: note: in expansion of macro 'BUILD_BUG_ON_MSG' > 50 | BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) > | ^~~~~~~~~~~~~~~~ > ./include/linux/nospec.h:56:2: note: in expansion of macro 'BUILD_BUG_ON' > 56 | BUILD_BUG_ON(sizeof(_s) > sizeof(long)); \ > | ^~~~~~~~~~~~ > drivers/vhost/vhost.c:2076:5: note: in expansion of macro 'array_index_nospec' > 2076 | array_index_nospec((unsigned long)(addr - node->start), > | ^~~~~~~~~~~~~~~~~~ > make[2]: *** [scripts/Makefile.build:281: drivers/vhost/vhost.o] Error 1 > make[1]: *** [scripts/Makefile.build:497: drivers/vhost] Error 2 > make: *** [Makefile:1083: drivers] Error 2 > > $ git revert a89db445fbd7f1f8457b03759aa7343fa530ef6b > > $ LANG= make ARCH=x86 -j16 bzImage modules > CALL scripts/atomic/check-atomics.sh > CALL scripts/checksyscalls.sh > CHK include/generated/compile.h > CHK kernel/kheaders_data.tar.xz > Building modules, stage 2. > Kernel: arch/x86/boot/bzImage is ready (#1) > MODPOST 3464 modules > > $ echo $? > 0 > > $ find . -name vhost\\.ko > ./drivers/vhost/vhost.ko > > I've attached the affected kernel config for v5.3~/ i386. Ok, good, we will be "bug compatible" at the very least now :) When this gets fixed in Linus's tree we can backport the fix here as well. The number of users of that compiler version/configuration is probably pretty low at the moment to want to hold off on this fix. thanks, greg k-h