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

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Message-ID: <eb07aa5a-e44c-67b7-e9c9-bd65602680ae@linux.dev>
Date:   Tue, 4 Apr 2023 17:10:49 -0700
From:   Martin KaFai Lau <martin.lau@...ux.dev>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     daniel@...earbox.net, andrii@...nel.org, martin.lau@...nel.org,
        void@...ifault.com, davemarchevsky@...a.com, tj@...nel.org,
        memxor@...il.com, netdev@...r.kernel.org, bpf@...r.kernel.org,
        kernel-team@...com, davem@...emloft.net
Subject: Re: [PATCH bpf-next 4/8] bpf: Teach verifier that certain helpers
 accept NULL pointer.

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.