[PATCH bpf-next] libbpf: Free btf_vmlinux when closing bpf_object

[PATCH bpf-next] libbpf: Free btf_vmlinux when closing bpf_object

[Hao Luo]

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>
---
 tools/lib/bpf/libbpf.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index b8afe2f5bc93..4c3967d94b6d 100644
--- 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++)
-- 
2.42.0.rc1.204.g551eb34607-goog

Re: [PATCH bpf-next] libbpf: Free btf_vmlinux when closing bpf_object

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <andrii@kernel.org>:

On Tue, 22 Aug 2023 12:38:40 -0700 you wrote:
> 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.
> 
> [...]

Here is the summary with links:
  - [bpf-next] libbpf: Free btf_vmlinux when closing bpf_object
    https://git.kernel.org/bpf/bpf-next/c/29d67fdebc42

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html