Re: [PATCH] nexthop: Annotate struct nh_res_table with __counted_by

[Gustavo A. R. Silva]

On 10/4/23 01:18, 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 nh_res_table.
>
> Cc: David Ahern <dsahern@xxxxxxxxxx>
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
> Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
> Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
> Cc: netdev@xxxxxxxxxxxxxxx
> Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci [1]
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>

Reviewed-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>

Thanks
--
Gustavo

> ---
>   include/net/nexthop.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/net/nexthop.h b/include/net/nexthop.h
> index 5dc4b4bba8a5..09f9a732e640 100644
> --- a/include/net/nexthop.h
> +++ b/include/net/nexthop.h
> @@ -92,7 +92,7 @@ struct nh_res_table {
>   	u32			unbalanced_timer;
>   
>   	u16			num_nh_buckets;
> -	struct nh_res_bucket	nh_buckets[];
> +	struct nh_res_bucket	nh_buckets[] __counted_by(num_nh_buckets);
>   };
>   
>   struct nh_grp_entry {