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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 66D88C4CEC9 for ; Wed, 18 Sep 2019 06:27:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2F95321924 for ; Wed, 18 Sep 2019 06:27:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568788071; bh=6Bp66dhnguOvsj+AWTcuGX7grWtd/Ey3/k8Ya37DBto=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=YWIna3vwlXxX9kmv6ILNXftTNHoENnIfOKrqMEWWXx3vb72XwK/kTuVJ1+XiGiJNJ GjReNMh2GDJc1sHR0gJpGsJdOpO4RxLVunqzEtLrGgpLEcvZtB7LQvnDMAnytFYLi7 XuzoKL10K02GH1D47OcPYNk0Tpq4kCyTkZFhs03g= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728260AbfIRG1t (ORCPT ); Wed, 18 Sep 2019 02:27:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:49724 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729753AbfIRG1m (ORCPT ); Wed, 18 Sep 2019 02:27:42 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 53A1821924; Wed, 18 Sep 2019 06:27:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568788061; bh=6Bp66dhnguOvsj+AWTcuGX7grWtd/Ey3/k8Ya37DBto=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KSxK4elrWiyvXa7Js6p7hbLI49WF/XwhrvOOtytVo88nPGu8TboAWTNaCda5VL6pj 5kZPD2CSzBVMyD29AQPkn83d9ncjrmYS2VUklq9BLC2xry42NrSD08kAAqVqYzaDo7 6svomaVoznjWH8EhuUK9x13TZ1EquGdXpkSMXuOI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Fuqian Huang , Paolo Bonzini Subject: [PATCH 5.2 45/85] KVM: x86: work around leak of uninitialized stack contents Date: Wed, 18 Sep 2019 08:19:03 +0200 Message-Id: <20190918061235.562781847@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20190918061234.107708857@linuxfoundation.org> References: <20190918061234.107708857@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Fuqian Huang commit 541ab2aeb28251bf7135c7961f3a6080eebcc705 upstream. Emulation of VMPTRST can incorrectly inject a page fault when passed an operand that points to an MMIO address. The page fault will use uninitialized kernel stack memory as the CR2 and error code. The right behavior would be to abort the VM with a KVM_EXIT_INTERNAL_ERROR exit to userspace; however, it is not an easy fix, so for now just ensure that the error code and CR2 are zero. Signed-off-by: Fuqian Huang Cc: stable@vger.kernel.org [add comment] Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/x86.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5265,6 +5265,13 @@ int kvm_write_guest_virt_system(struct k /* kvm_write_guest_virt_system can pull in tons of pages. */ vcpu->arch.l1tf_flush_l1d = true; + /* + * FIXME: this should call handle_emulation_failure if X86EMUL_IO_NEEDED + * is returned, but our callers are not ready for that and they blindly + * call kvm_inject_page_fault. Ensure that they at least do not leak + * uninitialized kernel stack memory into cr2 and error code. + */ + memset(exception, 0, sizeof(*exception)); return kvm_write_guest_virt_helper(addr, val, bytes, vcpu, PFERR_WRITE_MASK, exception); }