Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754307AbdIRLIT (ORCPT ); Mon, 18 Sep 2017 07:08:19 -0400 Received: from mga01.intel.com ([192.55.52.88]:53053 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753815AbdIRLIR (ORCPT ); Mon, 18 Sep 2017 07:08:17 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.42,412,1500966000"; d="scan'208";a="1173260562" From: Yu Zhang To: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, pbonzini@redhat.com, jmattson@google.com, rkrcmar@redhat.com, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com Subject: [PATCH] KVM: x86: Fix the NULL pointer parameter in check_cr_write() Date: Mon, 18 Sep 2017 18:45:01 +0800 Message-Id: <1505731501-6821-1-git-send-email-yu.c.zhang@linux.intel.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1138 Lines: 34 Routine check_cr_write() will trigger emulator_get_cpuid()-> kvm_cpuid() to get maxphyaddr, and NULL is passed as values for ebx/ecx/edx. This is problematic because kvm_cpuid() will dereference these pointers. Fixes: d1cd3ce90044 ("KVM: MMU: check guest CR3 reserved bits based on its physical address width.") Reported-by: Jim Mattson Signed-off-by: Yu Zhang --- arch/x86/kvm/emulate.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 16bf665..15f527b 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -4102,10 +4102,12 @@ static int check_cr_write(struct x86_emulate_ctxt *ctxt) ctxt->ops->get_msr(ctxt, MSR_EFER, &efer); if (efer & EFER_LMA) { u64 maxphyaddr; - u32 eax = 0x80000008; + u32 eax, ebx, ecx, edx; - if (ctxt->ops->get_cpuid(ctxt, &eax, NULL, NULL, - NULL, false)) + eax = 0x80000008; + ecx = 0; + if (ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, + &edx, false)) maxphyaddr = eax & 0xff; else maxphyaddr = 36; -- 2.5.0