* [PATCH] KVM: lapic: Check for in-kernel LAPIC before deferencing apic pointer
@ 2019-04-26 2:01 Sean Christopherson
2019-04-26 3:15 ` Konrad Rzeszutek Wilk
0 siblings, 1 reply; 3+ messages in thread
From: Sean Christopherson @ 2019-04-26 2:01 UTC (permalink / raw)
To: Paolo Bonzini, Radim Krčmář
Cc: kvm, syzbot+f7e65445a40d3e0e4ebf
...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>
---
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 7decd58c9cea..35b8ac8f04fe 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1487,9 +1487,6 @@ 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 aa26a3cfc765..21cb34d8ae01 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7872,7 +7872,8 @@ 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();
--
2.21.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: lapic: Check for in-kernel LAPIC before deferencing apic pointer
2019-04-26 2:01 [PATCH] KVM: lapic: Check for in-kernel LAPIC before deferencing apic pointer Sean Christopherson
@ 2019-04-26 3:15 ` Konrad Rzeszutek Wilk
2019-04-30 19:17 ` Paolo Bonzini
0 siblings, 1 reply; 3+ messages in thread
From: Konrad Rzeszutek Wilk @ 2019-04-26 3:15 UTC (permalink / raw)
To: Sean Christopherson
Cc: Paolo Bonzini, Radim Krčmář, kvm,
syzbot+f7e65445a40d3e0e4ebf
On Thu, Apr 25, 2019 at 07:01:09PM -0700, Sean Christopherson wrote:
> ...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
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
> 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 7decd58c9cea..35b8ac8f04fe 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -1487,9 +1487,6 @@ 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 aa26a3cfc765..21cb34d8ae01 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -7872,7 +7872,8 @@ 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();
>
> --
> 2.21.0
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: lapic: Check for in-kernel LAPIC before deferencing apic pointer
2019-04-26 3:15 ` Konrad Rzeszutek Wilk
@ 2019-04-30 19:17 ` Paolo Bonzini
0 siblings, 0 replies; 3+ messages in thread
From: Paolo Bonzini @ 2019-04-30 19:17 UTC (permalink / raw)
To: Konrad Rzeszutek Wilk, Sean Christopherson
Cc: Radim Krčmář, kvm, syzbot+f7e65445a40d3e0e4ebf
On 26/04/19 05:15, Konrad Rzeszutek Wilk wrote:
> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Queued, thanks.
Paolo
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2019-04-30 19:17 UTC | newest]
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2019-04-26 2:01 [PATCH] KVM: lapic: Check for in-kernel LAPIC before deferencing apic pointer Sean Christopherson
2019-04-26 3:15 ` Konrad Rzeszutek Wilk
2019-04-30 19:17 ` Paolo Bonzini
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