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SubjectRe: [PATCH] net/packet: Annotate struct packet_fanout with __counted_by
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On 10/4/23 01:17, 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 packet_fanout.
>
> 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: Willem de Bruijn <willemb@google.com>
> Cc: Anqi Shen <amy.saq@antgroup.com>
> Cc: netdev@vger.kernel.org
> 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

> ---
> net/packet/internal.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/packet/internal.h b/net/packet/internal.h
> index 63f4865202c1..d29c94c45159 100644
> --- a/net/packet/internal.h
> +++ b/net/packet/internal.h
> @@ -94,7 +94,7 @@ struct packet_fanout {
> spinlock_t lock;
> refcount_t sk_ref;
> struct packet_type prot_hook ____cacheline_aligned_in_smp;
> - struct sock __rcu *arr[];
> + struct sock __rcu *arr[] __counted_by(max_num_members);
> };
>
> struct packet_rollover {

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