libbpf: Free btf_vmlinux when closing bpf_object

I hit a memory leak when testing bpf_program__set_attach_target().
Basically, set_attach_target() may allocate btf_vmlinux, for example,
when setting attach target for bpf_iter programs. But btf_vmlinux
is freed only in bpf_object_load(), which means if we only open
bpf object but not load it, setting attach target may leak
btf_vmlinux.

So let's free btf_vmlinux in bpf_object__close() anyway.

Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230822193840.1509809-1-haoluo@google.com

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index b8afe2f5bc9347d5fec67f4375f2c7fac5722dd9..4c3967d94b6d3ff9b19778f98e925db60086e3d6 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -8423,6 +8423,7 @@ void bpf_object__close(struct bpf_object *obj)
        bpf_object__elf_finish(obj);
        bpf_object_unload(obj);
        btf__free(obj->btf);
+       btf__free(obj->btf_vmlinux);
        btf_ext__free(obj->btf_ext);
 
        for (i = 0; i < obj->nr_maps; i++)