On 7/29/25 2:45 AM, Achill Gilgenast wrote:
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;
| ^~~~~~~
Fixes: 8f8a024272f3 ("libbpf: support "module: Function" syntax for tracing programs")
Signed-off-by: Achill Gilgenast <fossdd@xxxxxxxxxx>
The code itself is actually okay. The error is triggered due to'maybe-uninitialized'.
To silence the compilation error, I think this change is okay.
Acked-by: Yonghong Song <yonghong.song@xxxxxxxxx>
---
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);
