From ecec76885bcfe3294685dc363fd1273df0d5d65f Mon Sep 17 00:00:00 2001
From: Peter Shier <pshier@google.com>
Date: Thu, 11 Oct 2018 11:46:46 -0700
Subject: [PATCH] KVM: nVMX: unconditionally cancel preemption timer in
 free_nested (CVE-2019-7221)

Bugzilla: 1671904

There are multiple code paths where an hrtimer may have been started to
emulate an L1 VMX preemption timer that can result in a call to free_nested
without an intervening L2 exit where the hrtimer is normally
cancelled. Unconditionally cancel in free_nested to cover all cases.

Embargoed until Feb 7th 2019.

Signed-off-by: Peter Shier <pshier@google.com>
Reported-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Reported-by: Felix Wilhelm <fwilhelm@google.com>
Cc: stable@kernel.org
Message-Id: <20181011184646.154065-1-pshier@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/vmx/nested.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 8ff20523661b..d8ea4ebd79e7 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -211,6 +211,7 @@ static void free_nested(struct kvm_vcpu *vcpu)
 	if (!vmx->nested.vmxon && !vmx->nested.smm.vmxon)
 		return;
 
+	hrtimer_cancel(&vmx->nested.preemption_timer);
 	vmx->nested.vmxon = false;
 	vmx->nested.smm.vmxon = false;
 	free_vpid(vmx->nested.vpid02);