From: Paul Mackerras Date: Wed, 10 Aug 2016 01:13:09 +0000 (+1000) Subject: KVM: PPC: Book3S: Don't crash if irqfd used with no in-kernel XICS emulation X-Git-Tag: v4.9-rc1~110^2~19^2~25 X-Git-Url: http://git.cascardo.eti.br/?a=commitdiff_plain;h=e48ba1cbce12eb4546771d45c09dd94c3404efe8;p=cascardo%2Flinux.git 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 --- diff --git a/arch/powerpc/kvm/book3s_xics.c b/arch/powerpc/kvm/book3s_xics.c index 05aa11399a78..686147efbac5 100644 --- a/arch/powerpc/kvm/book3s_xics.c +++ b/arch/powerpc/kvm/book3s_xics.c @@ -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); }