linux-kernel - [PATCH AUTOSEL 5.4 09/10] libbpf: Free btf_vmlinux when closing bpf

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Message-Id: <20230908182046.3460968-9-sashal@kernel.org>
Date:   Fri,  8 Sep 2023 14:20:43 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Hao Luo <haoluo@...gle.com>, Andrii Nakryiko <andrii@...nel.org>,
        Sasha Levin <sashal@...nel.org>, ast@...nel.org,
        daniel@...earbox.net, bpf@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 09/10] libbpf: Free btf_vmlinux when closing bpf_object

From: Hao Luo <haoluo@...gle.com>

[ Upstream commit 29d67fdebc42af6466d1909c60fdd1ef4f3e5240 ]

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@...gle.com>
Signed-off-by: Andrii Nakryiko <andrii@...nel.org>
Link: https://lore.kernel.org/bpf/20230822193840.1509809-1-haoluo@google.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 b8849812449c3..343018632d2d1 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4202,6 +4202,7 @@ 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++) {
-- 
2.40.1