Subject: Re: [PATCH bpf-next 4/8] bpf: Teach verifier that certain helpers accept NULL pointer.

From: Martin KaFai Lau <[email-masked]>
Date: Tue, 4 Apr 2023 17:10:49 -0700

On 4/3/23 9:50 PM, Alexei Starovoitov wrote:
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 1f2abf0f60e6..727c5269867d 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -4998,7 +4998,7 @@ const struct bpf_func_proto bpf_get_socket_ptr_cookie_proto = {
>   	.func		= bpf_get_socket_ptr_cookie,
>   	.gpl_only	= false,
>   	.ret_type	= RET_INTEGER,
> -	.arg1_type	= ARG_PTR_TO_BTF_ID_SOCK_COMMON,
> +	.arg1_type	= ARG_PTR_TO_BTF_ID_SOCK_COMMON | PTR_MAYBE_NULL,

I think the bpf_skc_to_* helpers (eg. bpf_skc_to_tcp_sock) also need similar 
change. They are available to tracing also. It can be a follow-up. The patch set 
lgtm.