| From 8c6de56a42e0c657955e12b882a81ef07d1d073e Mon Sep 17 00:00:00 2001 |
| From: Boris Ostrovsky <boris.ostrovsky@oracle.com> |
| Date: Wed, 30 Oct 2019 19:01:31 +0000 |
| Subject: x86/kvm: Be careful not to clear KVM_VCPU_FLUSH_TLB bit |
| |
| From: Boris Ostrovsky <boris.ostrovsky@oracle.com> |
| |
| commit 8c6de56a42e0c657955e12b882a81ef07d1d073e upstream. |
| |
| 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/x86/kvm/x86.c | 3 +++ |
| 1 file changed, 3 insertions(+) |
| |
| --- a/arch/x86/kvm/x86.c |
| +++ b/arch/x86/kvm/x86.c |
| @@ -3244,6 +3244,9 @@ static void kvm_steal_time_set_preempted |
| 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, |
