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From:   Yuntao Wang <ytcoode@gmail.com>
To:     andrii.nakryiko@gmail.com
Cc:     andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org,
        daniel@iogearbox.net, john.fastabend@gmail.com, kafai@fb.com,
        kpsingh@kernel.org, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, songliubraving@fb.com, yhs@fb.com,
        ytcoode@gmail.com, toke@redhat.com
Subject: [PATCH bpf-next v2] libbpf: Don't return -EINVAL if hdr_len < offsetofend(core_relo_len)
Date:   Wed, 16 Mar 2022 22:52:13 +0800
Message-Id: <20220316145213.868746-1-ytcoode@gmail.com>
In-Reply-To: <CAEf4BzbzqvQM63-mO96tbNaPXsKSbff4h-mX6UBfbU9zZG67OQ@mail.gmail.com>
References: <CAEf4BzbzqvQM63-mO96tbNaPXsKSbff4h-mX6UBfbU9zZG67OQ@mail.gmail.com>
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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