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| author | Boris Ostrovsky <boris.ostrovsky@oracle.com> | 2019-10-30 19:01:31 +0000 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-01-30 18:45:54 +0100 |
| commit | 8c6de56a42e0c657955e12b882a81ef07d1d073e (patch) | |
| tree | 46a20e7ac5a0365ffa0d5bf414955ebf3f36db46 /arch/x86/kvm/x86.c | |
| parent | ae6088216ce4b99b3a4aaaccd2eb2dd40d473d42 (diff) | |
| download | lwn-8c6de56a42e0c657955e12b882a81ef07d1d073e.tar.gz lwn-8c6de56a42e0c657955e12b882a81ef07d1d073e.zip | |
x86/kvm: Be careful not to clear KVM_VCPU_FLUSH_TLB bit
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>
Diffstat (limited to 'arch/x86/kvm/x86.c')
| -rw-r--r-- | arch/x86/kvm/x86.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index cf917139de6b..8c9369151e9f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3504,6 +3504,9 @@ 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 = KVM_VCPU_PREEMPTED; kvm_write_guest_offset_cached(vcpu->kvm, &vcpu->arch.st.stime, |