From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757751Ab0CaAg6 (ORCPT ); Tue, 30 Mar 2010 20:36:58 -0400 Received: from kroah.org ([198.145.64.141]:48567 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755920Ab0C3XJP (ORCPT ); Tue, 30 Mar 2010 19:09:15 -0400 X-Mailbox-Line: From linux@linux.site Tue Mar 30 15:50:01 2010 Message-Id: <20100330225000.970252456@linux.site> User-Agent: quilt/0.47-14.9 Date: Tue, 30 Mar 2010 15:48:52 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Marcelo Tosatti , Avi Kivity , Greg Kroah-Hartman Subject: [32/45] KVM: x86: check for cr3 validity in ioctl_set_sregs In-Reply-To: <20100330230410.GA28712@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: Marcelo Tosatti commit 59839dfff5eabca01cc4e20b45797a60a80af8cb upstream. Matt T. Yourst notes that kvm_arch_vcpu_ioctl_set_sregs lacks validity checking for the new cr3 value: "Userspace callers of KVM_SET_SREGS can pass a bogus value of cr3 to the kernel. This will trigger a NULL pointer access in gfn_to_rmap() when userspace next tries to call KVM_RUN on the affected VCPU and kvm attempts to activate the new non-existent page table root. This happens since kvm only validates that cr3 points to a valid guest physical memory page when code *inside* the guest sets cr3. However, kvm currently trusts the userspace caller (e.g. QEMU) on the host machine to always supply a valid page table root, rather than properly validating it along with the rest of the reloaded guest state." http://sourceforge.net/tracker/?func=detail&atid=893831&aid=2687641&group_id=180599 Check for a valid cr3 address in kvm_arch_vcpu_ioctl_set_sregs, triple fault in case of failure. Signed-off-by: Marcelo Tosatti Signed-off-by: Avi Kivity Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/x86.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3658,7 +3658,13 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct vcpu->arch.cr2 = sregs->cr2; mmu_reset_needed |= vcpu->arch.cr3 != sregs->cr3; - vcpu->arch.cr3 = sregs->cr3; + + down_read(&vcpu->kvm->slots_lock); + if (gfn_to_memslot(vcpu->kvm, sregs->cr3 >> PAGE_SHIFT)) + vcpu->arch.cr3 = sregs->cr3; + else + set_bit(KVM_REQ_TRIPLE_FAULT, &vcpu->requests); + up_read(&vcpu->kvm->slots_lock); kvm_set_cr8(vcpu, sregs->cr8);