Re: [PATCH RFC 07/15] arm_mpam: Fix the RIS index range check in mpam_ris_create_locked

[Andre Przywara]

Hi,

On 8/11/26 15:30, Yin Li wrote:
> The RIS selector field is defined as MPAMCFG_PART_SEL_RIS (bits 27:24),
> which is 4 bits wide and gives valid indices 0..15. MPAM_MSC_MAX_NUM_RIS
> is defined as 16, so the check should use >= to reject index 16 and
> above. The previous > check incorrectly accepted index 16 as valid.

Indeed. Either the maintainers pick this one independently, or put it up 
front in any repost.

And add:
Fixes: 01fb4b822472 ("arm_mpam: Add the class and component structures 
for firmware described ris")

> Signed-off-by: Yin Li <yin.li@xxxxxxxxxxxxxxxx>

Reviewed-by: Andre Przywara <andre.przywara@xxxxxxx>

Cheers,
Andre

> ---
>   drivers/resctrl/mpam_devices.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
> index ddc15249ec1e..cc9fa1d78925 100644
> --- a/drivers/resctrl/mpam_devices.c
> +++ b/drivers/resctrl/mpam_devices.c
> @@ -725,7 +725,7 @@ static int mpam_ris_create_locked(struct mpam_msc *msc, u8 ris_idx,
>   
>   	lockdep_assert_held(&mpam_list_lock);
>   
> -	if (ris_idx > MPAM_MSC_MAX_NUM_RIS)
> +	if (ris_idx >= MPAM_MSC_MAX_NUM_RIS)
>   		return -EINVAL;
>   
>   	if (test_and_set_bit(ris_idx, &msc->ris_idxs))