39 lines
1.3 KiB
Diff
39 lines
1.3 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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Date: Fri, 31 Jan 2020 08:06:40 -0300
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Subject: [PATCH] x86/kvm: Be careful not to clear KVM_VCPU_FLUSH_TLB bit
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CVE-2019-3016
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CVE-2020-3016
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kvm_steal_time_set_preempted() may accidentally clear KVM_VCPU_FLUSH_TLB
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bit if it is called more than once while VCPU is preempted.
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This is part of CVE-2019-3016.
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(This bug was also independently discovered by Jim Mattson
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<jmattson@google.com>)
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Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
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Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
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Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
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---
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arch/x86/kvm/x86.c | 3 +++
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1 file changed, 3 insertions(+)
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diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
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index 778b3a899769..92d8e4ebba16 100644
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--- a/arch/x86/kvm/x86.c
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+++ b/arch/x86/kvm/x86.c
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@@ -3393,6 +3393,9 @@ static void kvm_steal_time_set_preempted(struct kvm_vcpu *vcpu)
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if (!(vcpu->arch.st.msr_val & KVM_MSR_ENABLED))
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return;
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+ if (vcpu->arch.st.steal.preempted)
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+ return;
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+
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vcpu->arch.st.steal.preempted = KVM_VCPU_PREEMPTED;
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kvm_write_guest_offset_cached(vcpu->kvm, &vcpu->arch.st.stime,
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