Subject: Re: [PATCH net-next v2 2/2] KEYS: annotate struct user_key_payload with __counted_by

From: Jarkko Sakkinen <[email-masked]>
Date: Wed, 15 Apr 2026 05:25:33 +0300

On Fri, Apr 10, 2026 at 12:57:05AM +0200, Thorsten Blum wrote:
> Add the __counted_by() compiler attribute to the flexible array member
> 'data' to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and
> CONFIG_FORTIFY_SOURCE.
> 
> Signed-off-by: Thorsten Blum <[email-masked]>
> ---
> Changes in v2:
> - Use __aligned(8) as suggested by David
> - v1: https://lore.kernel.org/lkml/[email-masked]/
> 
> Cc: [email-masked]
> ---
>  include/keys/user-type.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/include/keys/user-type.h b/include/keys/user-type.h
> index 386c31432789..c29ed9f5d300 100644
> --- a/include/keys/user-type.h
> +++ b/include/keys/user-type.h
> @@ -27,7 +27,8 @@
>  struct user_key_payload {
>  	struct rcu_head	rcu;		/* RCU destructor */
>  	unsigned short	datalen;	/* length of this data */
> -	char		data[] __aligned(__alignof__(u64)); /* actual data */
> +	char		data[]		/* actual data */
> +			__aligned(8) __counted_by(datalen);
>  };
>  
>  extern struct key_type key_type_user;

The change is acceptable but I see no point split the declaration into
two lines (as long as it passes checkpatch.pl as per line length).

BR, Jarkko