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From:   Yuntao Wang <ytcoode@gmail.com>
To:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>
Cc:     Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
        Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>, netdev@vger.kernel.org,
        bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
        Yuntao Wang <ytcoode@gmail.com>
Subject: [PATCH bpf-next] libbpf: Remove redundant check in btf_ext__new()
Date:   Sun, 13 Mar 2022 01:13:54 +0800
Message-Id: <20220312171354.661448-1-ytcoode@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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@gmail.com>
---
 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;
-	}
-
 	err = btf_ext_setup_core_relos(btf_ext);
 	if (err)
 		goto done;
-- 
2.35.1