FAILED: patch "[PATCH] KVM: nVMX: update last_nonleaf_level when initializing nested" failed to apply to 4.4-stable tree

FAILED: patch "[PATCH] KVM: nVMX: update last_nonleaf_level when initializing nested" failed to apply to 4.4-stable tree

[gregkh]

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From fd19d3b45164466a4adce7cbff448ba9189e1427 Mon Sep 17 00:00:00 2001
From: Ladi Prosek <lprosek@redhat.com>
Date: Thu, 5 Oct 2017 11:10:22 +0200
Subject: [PATCH] KVM: nVMX: update last_nonleaf_level when initializing nested
 EPT

The function updates context->root_level but didn't call
update_last_nonleaf_level so the previous and potentially wrong value
was used for page walks.  For example, a zero value of last_nonleaf_level
would allow a potential out-of-bounds access in arch/x86/mmu/paging_tmpl.h's
walk_addr_generic function (CVE-2017-12188).

Fixes: 155a97a3d7c78b46cef6f1a973c831bc5a4f82bb
Signed-off-by: Ladi Prosek <lprosek@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 106d4a029a8a..3c25f20115bc 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -4555,6 +4555,7 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
 
 	update_permission_bitmask(vcpu, context, true);
 	update_pkru_bitmask(vcpu, context, true);
+	update_last_nonleaf_level(vcpu, context);
 	reset_rsvds_bits_mask_ept(vcpu, context, execonly);
 	reset_ept_shadow_zero_bits_mask(vcpu, context, execonly);
 }

Re: FAILED: patch "[PATCH] KVM: nVMX: update last_nonleaf_level when initializing nested" failed to apply to 4.4-stable tree

[Paolo Bonzini]

On 16/10/2017 18:03, gregkh@linuxfoundation.org wrote:
> The patch below does not apply to the 4.4-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.

It's okay not to apply the patch; the bug was only latent before 4.6.

Paolo

Re: FAILED: patch "[PATCH] KVM: nVMX: update last_nonleaf_level when initializing nested" failed to apply to 4.4-stable tree

[Greg KH]

On Mon, Oct 16, 2017 at 06:06:43PM +0200, Paolo Bonzini wrote:
> On 16/10/2017 18:03, gregkh@linuxfoundation.org wrote:
> > The patch below does not apply to the 4.4-stable tree.
> > If someone wants it applied there, or to any other stable or longterm
> > tree, then please email the backport, including the original git commit
> > id to <stable@vger.kernel.org>.
> 
> It's okay not to apply the patch; the bug was only latent before 4.6.

That's not what the patch itself said :)

Anyway, thanks for the quick response, I'll leave this alone for 4.4.

greg k-h