linux-kernel - [PATCH v2] libbpf: Initialize st

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Message-ID: <20240821112344.54299-3-soma.nakata01@gmail.com>
Date: Wed, 21 Aug 2024 20:23:46 +0900
From: Soma Nakata <soma.nakata01@...il.com>
To: Andrii Nakryiko <andrii@...nel.org>,
	Eduard Zingerman <eddyz87@...il.com>,
	Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	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>
Cc: soma.nakata01@...il.com,
	bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2] libbpf: Initialize st_ops->tname with strdup()

`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 | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index a3be6f8fac09..f4ad1b993ec5 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -496,7 +496,7 @@ struct bpf_program {
 };
 
 struct bpf_struct_ops {
-	const char *tname;
+	char *tname;
 	const struct btf_type *type;
 	struct bpf_program **progs;
 	__u32 *kern_func_off;
@@ -1423,7 +1423,9 @@ 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);
+		if (!st_ops->tname)
+			return -ENOMEM;
 		st_ops->type = type;
 		st_ops->type_id = type_id;
 
@@ -8984,6 +8986,7 @@ static void bpf_map__destroy(struct bpf_map *map)
 	map->mmaped = NULL;
 
 	if (map->st_ops) {
+		zfree(&map->st_ops->tname);
 		zfree(&map->st_ops->data);
 		zfree(&map->st_ops->progs);
 		zfree(&map->st_ops->kern_func_off);
-- 
2.46.0