Re: [PATCH] audit: Annotate struct audit_chunk with __counted_by

[Paul Moore]

On Thu, Aug 17, 2023 at 4:35 PM Kees Cook <keescook@xxxxxxxxxxxx> 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 audit_chunk.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Paul Moore <paul@xxxxxxxxxxxxxx>
> Cc: Eric Paris <eparis@xxxxxxxxxx>
> Cc: audit@xxxxxxxxxxxxxxx
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
>  kernel/audit_tree.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

This looks good to me, but considering we are currently at -rc6 I'd
prefer to hold off until after the upcoming merge window.  I'll send
another note once it's been merged into audit/next.

Thanks.

> diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
> index e867c17d3f84..85a5b306733b 100644
> --- a/kernel/audit_tree.c
> +++ b/kernel/audit_tree.c
> @@ -34,7 +34,7 @@ struct audit_chunk {
>                 struct list_head list;
>                 struct audit_tree *owner;
>                 unsigned index;         /* index; upper bit indicates 'will prune' */
> -       } owners[];
> +       } owners[] __counted_by(count);
>  };
>
>  struct audit_tree_mark {
> --
> 2.34.1

-- 
paul-moore.com