Re: [PATCH v8 2/5] arm64: Tighten the PR_{SET,GET}_TAGGED_ADDR_CTRL prctl() unused arguments

[Andrey Konovalov <andreyknvl@google.com>]

On Thu, Aug 15, 2019 at 5:44 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
>
> Require that arg{3,4,5} of the PR_{SET,GET}_TAGGED_ADDR_CTRL prctl and
> arg2 of the PR_GET_TAGGED_ADDR_CTRL prctl() are zero rather than ignored
> for future extensions.
>
> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Acked-by: Andrey Konovalov <andreyknvl@google.com>

> ---
>  kernel/sys.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/kernel/sys.c b/kernel/sys.c
> index c6c4d5358bd3..ec48396b4943 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -2499,9 +2499,13 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
>                 error = PAC_RESET_KEYS(me, arg2);
>                 break;
>         case PR_SET_TAGGED_ADDR_CTRL:
> +               if (arg3 || arg4 || arg5)
> +                       return -EINVAL;
>                 error = SET_TAGGED_ADDR_CTRL(arg2);
>                 break;
>         case PR_GET_TAGGED_ADDR_CTRL:
> +               if (arg2 || arg3 || arg4 || arg5)
> +                       return -EINVAL;
>                 error = GET_TAGGED_ADDR_CTRL();
>                 break;
>         default: