Subject: Re: [PATCH] nfp: Annotate struct nfp_reprs with __counted_by

From: Louis Peens <[email-masked]>
Date: Wed, 4 Oct 2023 07:13:00 +0200

On Tue, Oct 03, 2023 at 04:18:43PM -0700, Kees Cook 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 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 nfp_reprs.
> 
> Cc: Simon Horman <[email-masked]>
> Cc: Jakub Kicinski <[email-masked]>
> Cc: "David S. Miller" <[email-masked]>
> Cc: Eric Dumazet <[email-masked]>
> Cc: Paolo Abeni <[email-masked]>
> Cc: [email-masked]
> Cc: [email-masked]
> Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci [1]
> Signed-off-by: Kees Cook <[email-masked]>
Thanks Kees

Acked-by: Louis Peens <[email-masked]>
> ---
>  drivers/net/ethernet/netronome/nfp/nfp_net_repr.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_repr.h b/drivers/net/ethernet/netronome/nfp/nfp_net_repr.h
> index 48a74accbbd3..77bf4198dbde 100644
> --- a/drivers/net/ethernet/netronome/nfp/nfp_net_repr.h
> +++ b/drivers/net/ethernet/netronome/nfp/nfp_net_repr.h
> @@ -18,7 +18,7 @@ struct nfp_port;
>   */
>  struct nfp_reprs {
>  	unsigned int num_reprs;
> -	struct net_device __rcu *reprs[];
> +	struct net_device __rcu *reprs[] __counted_by(num_reprs);
>  };
>  
>  /**
> -- 
> 2.34.1
>