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

Gustavo A. R. Silva
2023-10-04T04:29:16Z

On 10/4/23 01:21, 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_notifier_grp_info.
>
> Cc: David Ahern <dsahern@kernel.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: Nathan Chancellor <nathan@kernel.org>
> Cc: Nick Desaulniers <ndesaulniers@google.com>
> Cc: Tom Rix <trix@redhat.com>
> Cc: netdev@vger.kernel.org
> Cc: llvm@lists.linux.dev
> Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci [1]
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

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 2b12725de9c0..5dc4b4bba8a5 100644
> --- a/include/net/nexthop.h
> +++ b/include/net/nexthop.h
> @@ -187,7 +187,7 @@ struct nh_notifier_grp_entry_info {
> struct nh_notifier_grp_info {
> u16 num_nh;
> bool is_fdb;
> - struct nh_notifier_grp_entry_info nh_entries[];
> + struct nh_notifier_grp_entry_info nh_entries[] __counted_by(num_nh);
> };
>
> struct nh_notifier_res_bucket_info {