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Message-ID: <20250801114613.610070-1-fossdd@pwned.life>
Date: Fri, 1 Aug 2025 13:46:06 +0200
From: Achill Gilgenast <fossdd@...ed.life>
To: Eduard Zingerman <eddyz87@...il.com>,
Yonghong Song <yonghong.song@...ux.dev>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>,
Viktor Malik <vmalik@...hat.com>,
bpf@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
Achill Gilgenast <fossdd@...ed.life>,
Martin KaFai Lau <martin.lau@...ux.dev>,
Song Liu <song@...nel.org>,
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>
Subject: [PATCH] libbpf: avoid possible use of uninitialized mod_len
If not fn_name, mod_len does never get initialized which fails now with
gcc15 on Alpine Linux edge:
libbpf.c: In function 'find_kernel_btf_id.constprop':
libbpf.c:10100:33: error: 'mod_len' may be used uninitialized [-Werror=maybe-uninitialized]
10100 | if (mod_name && strncmp(mod->name, mod_name, mod_len) != 0)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
libbpf.c:10070:21: note: 'mod_len' was declared here
10070 | int ret, i, mod_len;
| ^~~~~~~
Signed-off-by: Achill Gilgenast <fossdd@...ed.life>
Acked-by: Yonghong Song <yonghong.song@...ux.dev>
Acked-by: Eduard Zingerman <eddyz87@...il.com>
Link: https://lore.kernel.org/bpf/20250729094611.2065713-1-fossdd@pwned.life/
---
tools/lib/bpf/libbpf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index e067cb5776bd..fb4d92c5c339 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -10086,27 +10086,27 @@ static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd, int t
btf__free(btf);
if (err <= 0) {
pr_warn("%s is not found in prog's BTF\n", name);
goto out;
}
out:
return err;
}
static int find_kernel_btf_id(struct bpf_object *obj, const char *attach_name,
enum bpf_attach_type attach_type,
int *btf_obj_fd, int *btf_type_id)
{
- int ret, i, mod_len;
+ int ret, i, mod_len = 0;
const char *fn_name, *mod_name = NULL;
fn_name = strchr(attach_name, ':');
if (fn_name) {
mod_name = attach_name;
mod_len = fn_name - mod_name;
fn_name++;
}
if (!mod_name || strncmp(mod_name, "vmlinux", mod_len) == 0) {
ret = find_attach_btf_id(obj->btf_vmlinux,
mod_name ? fn_name : attach_name,
attach_type);
--
2.50.1
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