From b904cb8dff824b79233e82c078837627ebd52717 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 25 Apr 2019 19:01:09 -0700 Subject: [PATCH] KVM: lapic: Check for in-kernel LAPIC before deferencing apic pointer ...to avoid dereferencing a null pointer when querying the per-vCPU timer advance. Fixes: 39497d7660d98 ("KVM: lapic: Track lapic timer advance per vCPU") Reported-by: syzbot+f7e65445a40d3e0e4ebf@syzkaller.appspotmail.com Signed-off-by: Sean Christopherson Reviewed-by: Konrad Rzeszutek Wilk Signed-off-by: Paolo Bonzini --- arch/x86/kvm/lapic.c | 3 --- arch/x86/kvm/x86.c | 3 ++- 2 files changed, 2 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index e0fa6fc0b2d8..bd13fdddbdc4 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -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; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 57621313dead..b5edc8e3ce1d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -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(); -- 2.30.2