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KVM: lapic: Check for in-kernel LAPIC before deferencing apic pointer

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...to avoid dereferencing a null pointer when querying the per-vCPU
timer advance.

Fixes: 39497d7660 ("KVM: lapic: Track lapic timer advance per vCPU")
Reported-by: syzbot+f7e65445a40d3e0e4ebf@syzkaller.appspotmail.com
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2019-04-25 19:01:09 -07:00 committed by Paolo Bonzini
parent 76d58e0f07
commit b904cb8dff
2 changed files with 2 additions and 4 deletions
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3
arch/x86/kvm/lapic.c
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@ -1507,9 +1507,6 @@ void wait_lapic_expire(struct kvm_vcpu *vcpu)
u32 timer_advance_ns = apic->lapic_timer.timer_advance_ns;
u64 guest_tsc, tsc_deadline, ns;
if (!lapic_in_kernel(vcpu))
return;
if (apic->lapic_timer.expired_tscdeadline == 0)
return;

3
arch/x86/kvm/x86.c
View File

@ -7894,7 +7894,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
}
trace_kvm_entry(vcpu->vcpu_id);
if (vcpu->arch.apic->lapic_timer.timer_advance_ns)
if (lapic_in_kernel(vcpu) &&
vcpu->arch.apic->lapic_timer.timer_advance_ns)
wait_lapic_expire(vcpu);
guest_enter_irqoff();