[ Upstream commit 8c6de56a42e0c657955e12b882a81ef07d1d073e ] kvm_steal_time_set_preempted() may accidentally clear KVM_VCPU_FLUSH_TLB bit if it is called more than once while VCPU is preempted. This is part of CVE-2019-3016. (This bug was also independently discovered by Jim Mattson <jmattson@xxxxxxxxxx>) Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Reviewed-by: Joao Martins <joao.m.martins@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- arch/x86/kvm/x86.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 09f47c837c258..3aed03942d7d4 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3075,6 +3075,9 @@ static void kvm_steal_time_set_preempted(struct kvm_vcpu *vcpu) if (!(vcpu->arch.st.msr_val & KVM_MSR_ENABLED)) return; + if (vcpu->arch.st.steal.preempted) + return; + vcpu->arch.st.steal.preempted = 1; kvm_write_guest_offset_cached(vcpu->kvm, &vcpu->arch.st.stime, -- 2.25.1
