From: Sean Christopherson sean.j.christopherson@intel.com
commit b904cb8dff824b79233e82c078837627ebd52717 upstream.
...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 sean.j.christopherson@intel.com Reviewed-by: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kvm/lapic.c | 3 --- arch/x86/kvm/x86.c | 3 ++- 2 files changed, 2 insertions(+), 4 deletions(-)
--- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1504,9 +1504,6 @@ void wait_lapic_expire(struct kvm_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;
--- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7886,7 +7886,8 @@ static int vcpu_enter_guest(struct kvm_v }
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();