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

Fixes: 1928254c5ccb ("LoongArch: KVM: Add irqfd support")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/kvm/20260525051714.485D51F000E9@smtp.kernel.org/ (local)
Reviewed-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Yanfei Xu <redacted>
---
 arch/loongarch/kvm/irqfd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/loongarch/kvm/irqfd.c b/arch/loongarch/kvm/irqfd.c
index f4f953b22419..40ed1081c4b6 100644
--- a/arch/loongarch/kvm/irqfd.c
+++ b/arch/loongarch/kvm/irqfd.c

@@ -51,7 +51,8 @@ int kvm_set_routing_entry(struct kvm *kvm,
                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)
                        return -EINVAL;

                return 0;
--

2.20.1