On Sat, Mar 12, 2022 at 9:14 AM Yuntao Wang <ytcoode@xxxxxxxxx> wrote:
>
> Since 'core_relo_len' is the last field of 'struct btf_ext_header', if
> 'xxx->hdr_len' is not less than 'offsetofend(xxx, core_relo_len)', then
> 'xxx->hdr_len' must also be not less than 'offsetofend(xxx, line_info_len)'.
>
> We can check 'xxx->hdr_len < offsetofend(xxx, core_relo_len)' first, if it
> passes, the 'xxx->hdr_len < offsetofend(xxx, line_info_len)' check will be
> redundant, it can be removed.
>
> Signed-off-by: Yuntao Wang <ytcoode@xxxxxxxxx>
> ---
> tools/lib/bpf/btf.c | 7 +------
> 1 file changed, 1 insertion(+), 6 deletions(-)
>
> diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
> index 1383e26c5d1f..d55b44124c3e 100644
> --- a/tools/lib/bpf/btf.c
> +++ b/tools/lib/bpf/btf.c
> @@ -2813,7 +2813,7 @@ struct btf_ext *btf_ext__new(const __u8 *data, __u32 size)
> if (err)
> goto done;
>
> - if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, line_info_len)) {
> + if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, core_relo_len)) {
> err = -EINVAL;
> goto done;
> }
> @@ -2826,11 +2826,6 @@ struct btf_ext *btf_ext__new(const __u8 *data, __u32 size)
> if (err)
> goto done;
>
> - if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, core_relo_len)) {
> - err = -EINVAL;
> - goto done;
> - }
it seems like it's actually a bug. If header is smaller then core
relos parsing should be skipped, I think. Maybe let's fix that
instead?
basically the logic should be:
1. if size of header is exactly == offsetof(core_relo_off) then skip core relos
2. otherwise check that it has enough size to cover core_relo_off and
core_relo_len, and error out if not
3. otherwise proceed to parsing core relos
> -
> err = btf_ext_setup_core_relos(btf_ext);
> if (err)
> goto done;
> --
> 2.35.1
>
