| From b904cb8dff824b79233e82c078837627ebd52717 Mon Sep 17 00:00:00 2001 |
| From: Sean Christopherson <sean.j.christopherson@intel.com> |
| Date: Thu, 25 Apr 2019 19:01:09 -0700 |
| Subject: KVM: lapic: Check for in-kernel LAPIC before deferencing apic pointer |
| |
| 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(); |
| |
