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authorBoris Ostrovsky <boris.ostrovsky@oracle.com>2019-10-30 19:01:31 +0000
committerPaolo Bonzini <pbonzini@redhat.com>2020-01-30 18:45:54 +0100
commit8c6de56a42e0c657955e12b882a81ef07d1d073e (patch)
tree46a20e7ac5a0365ffa0d5bf414955ebf3f36db46 /arch
parentae6088216ce4b99b3a4aaaccd2eb2dd40d473d42 (diff)
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')
-rw-r--r--arch/x86/kvm/x86.c3
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,

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