| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.14 08/51] x86/kvm: Be careful not to clear KVM_VCPU_FLUSH_TLB bit | Date | Mon, 3 Aug 2020 14:19:53 +0200 |
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[ 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@google.com>)
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Reviewed-by: Joao Martins <joao.m.martins@oracle.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> --- 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
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