[PATCH] landlock: Annotate struct landlock_rule with __counted_by

[Justin Stitt]

On Thu, Aug 17, 2023 at 2:03 PM Kees Cook <keescook at chromium.org> wrote:
>
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
>
> As found with Coccinelle[1], add __counted_by for struct landlock_rule.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: "Mickaël Salaün" <mic at digikod.net>
> Cc: Paul Moore <paul at paul-moore.com>
> Cc: James Morris <jmorris at namei.org>
> Cc: "Serge E. Hallyn" <serge at hallyn.com>
> Cc: linux-security-module at vger.kernel.org
> Signed-off-by: Kees Cook <keescook at chromium.org>
Reviewed-by: Justin Stitt <justinstitt at google.com>

> ---
>  security/landlock/ruleset.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
> index d43231b783e4..55b1df8f66a8 100644
> --- a/security/landlock/ruleset.h
> +++ b/security/landlock/ruleset.h
> @@ -67,7 +67,7 @@ struct landlock_rule {
>          * @layers: Stack of layers, from the latest to the newest, implemented
>          * as a flexible array member (FAM).
>          */
> -       struct landlock_layer layers[];
> +       struct landlock_layer layers[] __counted_by(num_layers);
>  };
>
>  /**
> --
> 2.34.1
>