update sources to Ubuntu-5.11.0-34.36

[pve-kernel.git] / patches / kernel / 0009-UBUNTU-SAUCE-KVM-nSVM-always-intercept-VMLOAD-VMSAVE.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Maxim Levitsky <mlevitsk@redhat.com>
Date: Thu, 29 Jul 2021 18:37:38 +0300
Subject: [PATCH] UBUNTU: SAUCE: KVM: nSVM: always intercept VMLOAD/VMSAVE when
 nested

If L1 disables VMLOAD/VMSAVE intercepts, and doesn't enable
Virtual VMLOAD/VMSAVE (currently not supported for the nested hypervisor),
then VMLOAD/VMSAVE must operate on the L1 physical memory, which is only
possible by making L0 intercept these instructions.

Failure to do so allowed the nested guest to run VMLOAD/VMSAVE unintercepted,
and thus read/write portions of the host physical memory.

This fixes CVE-2021-3656, which was discovered by Maxim Levitsky and
Paolo Bonzini.

Fixes: 89c8a4984fc9 ("KVM: SVM: Enable Virtual VMLOAD VMSAVE feature")
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
CVE-2021-3656
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Ben Romer <benjamin.romer@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
(cherry picked from commit 7e23c00e809c1669676363962e2ef9df1bd2840b)
Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
---
 arch/x86/kvm/svm/nested.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 049d3cbbee5a..3bd5c7d6716e 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -147,6 +147,9 @@ void recalc_intercepts(struct vcpu_svm *svm)
 
 	for (i = 0; i < MAX_INTERCEPT; i++)
 		c->intercepts[i] |= g->intercepts[i];
+
+	vmcb_set_intercept(c, INTERCEPT_VMLOAD);
+	vmcb_set_intercept(c, INTERCEPT_VMSAVE);
 }
 
 static void copy_vmcb_control_area(struct vmcb_control_area *dst,