linux-kernel - Re: [PATCH] libbpf: Initialize st

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Message-ID: <CAEf4BzaDWU4EEOU+s2tGhNHfqjSZjdyZCU-b=Ws7Lz7NOo7p1A@mail.gmail.com>
Date: Wed, 21 Aug 2024 09:48:02 -0700
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Soma Nakata <soma.nakata01@...il.com>
Cc: Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, 
	Andrii Nakryiko <andrii@...nel.org>, Martin KaFai Lau <martin.lau@...ux.dev>, 
	Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>, 
	Yonghong Song <yonghong.song@...ux.dev>, John Fastabend <john.fastabend@...il.com>, 
	KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, 
	Jiri Olsa <jolsa@...nel.org>, bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] libbpf: Initialize st_ops->tname with strdup()

On Tue, Aug 20, 2024 at 11:48 PM Soma Nakata <soma.nakata01@...il.com> wrote:
>
> `tname` is returned by `btf__name_by_offset()` as well as `var_name`,
> and these addresses point to strings in the btf. Since their locations
> may change while loading the bpf program, using `strdup()` ensures
> `tname` is safely stored.
>
> Signed-off-by: Soma Nakata <soma.nakata01@...il.com>
> ---
>  tools/lib/bpf/libbpf.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index a3be6f8fac09..ece1f1af2cd4 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -1423,7 +1423,7 @@ static int init_struct_ops_maps(struct bpf_object *obj, const char *sec_name,
>                 memcpy(st_ops->data,
>                        data->d_buf + vsi->offset,
>                        type->size);
> -               st_ops->tname = tname;
> +               st_ops->tname = strdup(tname);
>                 st_ops->type = type;
>                 st_ops->type_id = type_id;
>

Thanks for the fix, but this has been fixed already ([0]). Please make
sure that you always reproduce the issue on bpf-next/master and send a
fix against that branch.

  [0] https://lore.kernel.org/bpf/20240724171459.281234-1-void@manifault.com/

pw-bot: cr

> --
> 2.46.0
>