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 mlxsw_sp_counter_pool.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Ido Schimmel <idosch@nvidia.com>
Cc: Petr Machata <petrm@nvidia.com>
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: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_cnt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_cnt.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_cnt.c
index ee59c79156e4..50e591420bd9 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_cnt.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_cnt.c
@@ -24,7 +24,7 @@ struct mlxsw_sp_counter_pool {
 	spinlock_t counter_pool_lock; /* Protects counter pool allocations */
 	atomic_t active_entries_count;
 	unsigned int sub_pools_count;
-	struct mlxsw_sp_counter_sub_pool sub_pools[];
+	struct mlxsw_sp_counter_sub_pool sub_pools[] __counted_by(sub_pools_count);
 };
 
 static const struct mlxsw_sp_counter_sub_pool mlxsw_sp_counter_sub_pools[] = {
-- 
2.34.1

On Fri, Sep 29, 2023 at 11:08 AM Kees Cook <keescook@chromium.org> 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 mlxsw_sp_counter_pool.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Ido Schimmel <idosch@nvidia.com>
> Cc: Petr Machata <petrm@nvidia.com>
> 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: netdev@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Justin Stitt <justinstitt@google.com>

> ---
>  drivers/net/ethernet/mellanox/mlxsw/spectrum_cnt.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_cnt.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_cnt.c
> index ee59c79156e4..50e591420bd9 100644
> --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_cnt.c
> +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_cnt.c
> @@ -24,7 +24,7 @@ struct mlxsw_sp_counter_pool {
>         spinlock_t counter_pool_lock; /* Protects counter pool allocations */
>         atomic_t active_entries_count;
>         unsigned int sub_pools_count;
> -       struct mlxsw_sp_counter_sub_pool sub_pools[];
> +       struct mlxsw_sp_counter_sub_pool sub_pools[] __counted_by(sub_pools_count);
>  };
>
>  static const struct mlxsw_sp_counter_sub_pool mlxsw_sp_counter_sub_pools[] = {
> --
> 2.34.1
>
>
Thanks
Justin

On Fri, Sep 29, 2023 at 11:07:42AM -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 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 mlxsw_sp_counter_pool.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Ido Schimmel <idosch@nvidia.com>
> Cc: Petr Machata <petrm@nvidia.com>
> 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: netdev@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Ido Schimmel <idosch@nvidia.com>