Sashiko reported that the irqchip index is not validated for PowerPC.
Add validation and reject out-of-range irqchip indexes to avoid indexing
past the routing table's chip array.

Fixes: de9ba2f36368 ("KVM: PPC: Support irq routing and irqfd for in-kernel 
MPIC")
Reported-by: Sashiko <[email protected]>
Closes: https://lore.kernel.org/kvm/[email protected]/
Reviewed-by: Harsh Prateek Bora <[email protected]>
Signed-off-by: Yanfei Xu <[email protected]>
---
 arch/powerpc/kvm/mpic.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/mpic.c b/arch/powerpc/kvm/mpic.c
index 3070f36d9fb8..fb5f9e65e02e 100644
--- a/arch/powerpc/kvm/mpic.c
+++ b/arch/powerpc/kvm/mpic.c
@@ -1833,7 +1833,8 @@ int kvm_set_routing_entry(struct kvm *kvm,
                e->set = mpic_set_irq;
                e->irqchip.irqchip = ue->u.irqchip.irqchip;
                e->irqchip.pin = ue->u.irqchip.pin;
-               if (e->irqchip.pin >= KVM_IRQCHIP_NUM_PINS)
+               if (e->irqchip.pin >= KVM_IRQCHIP_NUM_PINS ||
+                   e->irqchip.irqchip >= KVM_NR_IRQCHIPS)
                        goto out;
                break;
        case KVM_IRQ_ROUTING_MSI:
-- 
2.20.1

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