[PATCH] RISC-V: KVM: fix off-by-one array access in SBI PMU

[Anup Patel]

On Fri, Feb 27, 2026 at 7:20 PM Radim Krčmář
<radim.krcmar at oss.qualcomm.com> wrote:
>
> The indexed array only has RISCV_KVM_MAX_COUNTERS elements.
> The out-of-bound access could have been performed by a guest, but it
> could only access another guest accessible data.
>
> Fixes: 8f0153ecd3bf ("RISC-V: KVM: Add skeleton support for perf")
> Signed-off-by: Radim Krčmář <radim.krcmar at oss.qualcomm.com>

Thanks for catching.

Reviewed-by: Anup Patel <anup at brainfault.org>

Queued this patch as fixes for Linux-7.0-rcX.

Thanks,
Anup

> ---
>  arch/riscv/kvm/vcpu_pmu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c
> index 4d8d5e9aa53d..aec6b293968b 100644
> --- a/arch/riscv/kvm/vcpu_pmu.c
> +++ b/arch/riscv/kvm/vcpu_pmu.c
> @@ -520,7 +520,7 @@ int kvm_riscv_vcpu_pmu_ctr_info(struct kvm_vcpu *vcpu, unsigned long cidx,
>  {
>         struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
>
> -       if (cidx > RISCV_KVM_MAX_COUNTERS || cidx == 1) {
> +       if (cidx >= RISCV_KVM_MAX_COUNTERS || cidx == 1) {
>                 retdata->err_val = SBI_ERR_INVALID_PARAM;
>                 return 0;
>         }
> --
> 2.51.2
>