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>
This commit is contained in:
Peter Shier 2018-10-11 11:46:46 -07:00 committed by Paolo Bonzini
parent 353c0956a6
commit ecec76885b

View File

@ -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);