Commit e48ba1cb authored Aug 10, 2016 by Paul Mackerras

KVM: PPC: Book3S: Don't crash if irqfd used with no in-kernel XICS emulation

It turns out that if userspace creates a pseries-type VM without
in-kernel XICS (interrupt controller) emulation, and then connects
an eventfd to the VM as an irqfd, and the eventfd gets signalled,
that the code will try to deliver an interrupt via the non-existent
XICS object and crash the host kernel with a NULL pointer dereference.

To fix this, we check for the presence of the XICS object before
trying to deliver the interrupt, and return with an error if not.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

parent 694d0d0b

arch/powerpc/kvm/book3s_xics.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -1252,6 +1252,8 @@ int kvm_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level,
		{
		struct kvmppc_xics *xics = kvm->arch.xics;

		if (!xics)
		return -ENODEV;
		return ics_deliver_irq(xics, irq, level);
		}