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

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 <[email protected]>.

thanks,

greg k-h

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

From: Ladi Prosek <[email protected]>
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).

index 106d4a029a8a..3c25f20115bc 100644
@@ -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);
 }

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

Paolo

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