From 71afaba4a2e98bb7bdeba5078370ab43d46e67a1 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Tue, 8 Jul 2014 12:09:00 +0100 Subject: KVM: ARM: vgic: plug irq injection race As it stands, nothing prevents userspace from injecting an interrupt before the guest's GIC is actually initialized. This goes unnoticed so far (as everything is pretty much statically allocated), but ends up exploding in a spectacular way once we switch to a more dynamic allocation (the GIC data structure isn't there yet). The fix is to test for the "ready" flag in the VGIC distributor before trying to inject the interrupt. Note that in order to avoid breaking userspace, we have to ignore what is essentially an error. Signed-off-by: Marc Zyngier Acked-by: Christoffer Dall --- virt/kvm/arm/vgic.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c index 37fd20d35759..9bdf181a00e2 100644 --- a/virt/kvm/arm/vgic.c +++ b/virt/kvm/arm/vgic.c @@ -1585,7 +1585,8 @@ out: int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int irq_num, bool level) { - if (vgic_update_irq_pending(kvm, cpuid, irq_num, level)) + if (likely(vgic_initialized(kvm)) && + vgic_update_irq_pending(kvm, cpuid, irq_num, level)) vgic_kick_vcpus(kvm); return 0; -- cgit v1.2.3