Re: [PATCH v2 bpf-next 1/3] libbpf: disassociate section handler on explicit bpf_program__set_type() call

[Stanislav Fomichev <sdf@google.com>]

On 03/24, Andrii Nakryiko wrote:
> If user explicitly overrides programs's type with
> bpf_program__set_type() API call, we need to disassociate whatever
> SEC_DEF handler libbpf determined initially based on program's SEC()
> definition, as it's not goind to be valid anymore and could lead to
> crashes and/or confusing failures.

> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
> ---
>   tools/lib/bpf/libbpf.c | 1 +
>   1 file changed, 1 insertion(+)

> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index f6a071db5c6e..a34ebb6b8508 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -8465,6 +8465,7 @@ int bpf_program__set_type(struct bpf_program *prog,  
> enum bpf_prog_type type)
>   		return libbpf_err(-EBUSY);

>   	prog->type = type;
> +	prog->sec_def = NULL;
>   	return 0;
>   }

Surprisingly, but it breaks the following selftest:

serial_test_bpf_obj_id:PASS:get-fd-by-notexist-prog-id 0 nsec
serial_test_bpf_obj_id:PASS:get-fd-by-notexist-map-id 0 nsec
serial_test_bpf_obj_id:PASS:get-fd-by-notexist-link-id 0 nsec
serial_test_bpf_obj_id:FAIL:prog_attach prog #0, err -95
   #17      bpf_obj_id:FAIL

(saw in the bot, reproduced locally)

> --
> 2.34.1