[PATCH bpf 2/2] libbpf: Prevent double close of btf objects

[Jiri Olsa <jolsa@kernel.org>]

Sashiko found possible double close of btf object fd [1],
which happens when strdup in load_module_btfs fails at which
point the obj->btf_module_cnt is already incremented.

The error path close btf fd and so does later cleanup code in
bpf_object_post_load_cleanup function.

[1] https://sashiko.dev/#/patchset/20260324081846.2334094-1-jolsa%40kernel.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/lib/bpf/libbpf.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index b60ac8094a9e..33e7a09915dd 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -5825,7 +5825,7 @@ static int load_module_btfs(struct bpf_object *obj)
 		if (err)
 			goto err_out;
 
-		mod_btf = &obj->btf_modules[obj->btf_module_cnt++];
+		mod_btf = &obj->btf_modules[obj->btf_module_cnt];
 
 		mod_btf->btf = btf;
 		mod_btf->id = id;
@@ -5835,6 +5835,7 @@ static int load_module_btfs(struct bpf_object *obj)
 			err = -ENOMEM;
 			goto err_out;
 		}
+		obj->btf_module_cnt++;
 		continue;
 
 err_out:
-- 
2.53.0