Since core relos is an optional part of the .BTF.ext ELF section, we should
skip parsing it instead of returning -EINVAL if header size is less than
offsetofend(struct btf_ext_header, core_relo_len).

Fixes: e9fc3ce99b34 ("libbpf: Streamline error reporting for high-level APIs")
Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
---
v1 -> v2: skip core relos if hdr_len < offsetofend(core_relo_len)

 tools/lib/bpf/btf.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 1383e26c5d1f..9b7196b21498 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -2826,10 +2826,8 @@ 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;
-	}
+	if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, core_relo_len))
+		goto done; // skip core relos parsing
 
 	err = btf_ext_setup_core_relos(btf_ext);
 	if (err)
-- 
2.35.1

On Wed, Mar 16, 2022 at 7:52 AM Yuntao Wang <ytcoode@gmail.com> wrote:
>
> Since core relos is an optional part of the .BTF.ext ELF section, we should
> skip parsing it instead of returning -EINVAL if header size is less than
> offsetofend(struct btf_ext_header, core_relo_len).
>
> Fixes: e9fc3ce99b34 ("libbpf: Streamline error reporting for high-level APIs")
> Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
> ---
> v1 -> v2: skip core relos if hdr_len < offsetofend(core_relo_len)
>

Seems like this never made it to Patchworks. Can you please trim down
the CC list and resubmit?

>  tools/lib/bpf/btf.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
> index 1383e26c5d1f..9b7196b21498 100644
> --- a/tools/lib/bpf/btf.c
> +++ b/tools/lib/bpf/btf.c
> @@ -2826,10 +2826,8 @@ 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;
> -       }
> +       if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, core_relo_len))
> +               goto done; // skip core relos parsing

don't use C++-style comments, only /* */

>
>         err = btf_ext_setup_core_relos(btf_ext);
>         if (err)
> --
> 2.35.1
>

Since core relos is an optional part of the .BTF.ext ELF section, we should
skip parsing it instead of returning -EINVAL if header size is less than
offsetofend(struct btf_ext_header, core_relo_len).

Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
---
v1 -> v2: skip core relos if hdr_len < offsetofend(core_relo_len)
v2 -> v3: fix comment style

 tools/lib/bpf/btf.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 1383e26c5d1f..d124e9e533f0 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -2826,10 +2826,8 @@ 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;
-	}
+	if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, core_relo_len))
+		goto done; /* skip core relos parsing */
 
 	err = btf_ext_setup_core_relos(btf_ext);
 	if (err)
-- 
2.35.1

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <andrii@kernel.org>:

On Mon,  4 Apr 2022 08:53:20 +0800 you wrote:
> Since core relos is an optional part of the .BTF.ext ELF section, we should
> skip parsing it instead of returning -EINVAL if header size is less than
> offsetofend(struct btf_ext_header, core_relo_len).
> 
> Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
> ---
> v1 -> v2: skip core relos if hdr_len < offsetofend(core_relo_len)
> v2 -> v3: fix comment style
> 
> [...]

Here is the summary with links:
  - [bpf-next,v3] libbpf: Don't return -EINVAL if hdr_len < offsetofend(core_relo_len)
    https://git.kernel.org/bpf/bpf-next/c/a6a86da847eb

You are awesome, thank you!
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