Re: [PATCH] KVM: Validate irqchip index for LoongArch and PowerPC

[Harsh Prateek Bora <harshpb@linux.ibm.com>]

+ cc: stable@vger.kernel.org

On 25/05/26 12:31 pm, Yanfei Xu wrote:
> Sashiko reported that irqchip index is not validated for LoongArch and
> 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")
> 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/
> Signed-off-by: Yanfei Xu <yanfei.xu@bytedance.com>
> ---
>   arch/loongarch/kvm/irqfd.c | 3 ++-
>   arch/powerpc/kvm/mpic.c    | 3 ++-
>   2 files changed, 4 insertions(+), 2 deletions(-)
> 
> 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;
> 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)

Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com> # PPC KVM
>   			goto out;
>   		break;
>   	case KVM_IRQ_ROUTING_MSI: