From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751507AbdAYJbS (ORCPT ); Wed, 25 Jan 2017 04:31:18 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42424 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751372AbdAYJbP (ORCPT ); Wed, 25 Jan 2017 04:31:15 -0500 Subject: Re: [PATCH] kvm: fix page struct leak in handle_vmon To: Paolo Bonzini , linux-kernel@vger.kernel.org, kvm@vger.kernel.org References: <1485255381-18069-1-git-send-email-pbonzini@redhat.com> Cc: dvyukov@google.com From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <0cdfcfea-f1f6-fbcb-887a-dae659e2b844@redhat.com> Date: Wed, 25 Jan 2017 10:31:13 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 MIME-Version: 1.0 In-Reply-To: <1485255381-18069-1-git-send-email-pbonzini@redhat.com> Content-Type: text/plain; charset=iso-8859-15 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Wed, 25 Jan 2017 09:31:16 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 24.01.2017 um 11:56 schrieb Paolo Bonzini: > handle_vmon gets a reference on VMXON region page, > but does not release it. Release the reference. > > Found by syzkaller; based on a patch by Dmitry. > > Reported-by: Dmitry Vyukov > Signed-off-by: Paolo Bonzini > --- > arch/x86/kvm/vmx.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 42cc3d6f4d20..0f7345035210 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -7085,13 +7085,18 @@ static int nested_vmx_check_vmptr(struct kvm_vcpu *vcpu, int exit_reason, > } > > page = nested_get_page(vcpu, vmptr); > - if (page == NULL || > - *(u32 *)kmap(page) != VMCS12_REVISION) { > + if (page == NULL) { > nested_vmx_failInvalid(vcpu); > + return kvm_skip_emulated_instruction(vcpu); > + } > + if (*(u32 *)kmap(page) != VMCS12_REVISION) { shouldn't we also check if kmap even returned a valid pointer before dereferencing it? David thinks so. > kunmap(page); > + nested_release_page_clean(page); > + nested_vmx_failInvalid(vcpu); > return kvm_skip_emulated_instruction(vcpu); > } > kunmap(page); > + nested_release_page_clean(page); > vmx->nested.vmxon_ptr = vmptr; > break; > case EXIT_REASON_VMCLEAR: > -- David