From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: [PATCH] KVM: nVMX: Trap unconditionally if msr bitmap access
 fails
Date: Sun, 17 Feb 2013 10:56:36 +0200
Message-ID: <20130217085636.GR9817@redhat.com>
References: <511D3103.2040005@siemens.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: Marcelo Tosatti <mtosatti@redhat.com>, kvm <kvm@vger.kernel.org>,
	"Nadav Har'El" <nyh@math.technion.ac.il>
To: Jan Kiszka <jan.kiszka@siemens.com>
Return-path: <kvm-owner@vger.kernel.org>
Received: from mx1.redhat.com ([209.132.183.28]:15575 "EHLO mx1.redhat.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1755254Ab3BQI4m (ORCPT <rfc822;kvm@vger.kernel.org>);
	Sun, 17 Feb 2013 03:56:42 -0500
Content-Disposition: inline
In-Reply-To: <511D3103.2040005@siemens.com>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

On Thu, Feb 14, 2013 at 07:46:27PM +0100, Jan Kiszka wrote:
> This avoids basing decisions on uninitialized variables, potentially
> leaking kernel data to the L1 guest.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Gleb Natapov <gleb@redhat.com>

> ---
>  arch/x86/kvm/vmx.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 2633199..81a25de 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -5991,7 +5991,8 @@ static bool nested_vmx_exit_handled_msr(struct kvm_vcpu *vcpu,
>  	/* Then read the msr_index'th bit from this bitmap: */
>  	if (msr_index < 1024*8) {
>  		unsigned char b;
> -		kvm_read_guest(vcpu->kvm, bitmap + msr_index/8, &b, 1);
> +		if (kvm_read_guest(vcpu->kvm, bitmap + msr_index/8, &b, 1))
> +			return 1;
>  		return 1 & (b >> (msr_index & 7));
>  	} else
>  		return 1; /* let L1 handle the wrong parameter */
> -- 
> 1.7.3.4

--
			Gleb.