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From:   Haowen Bai <baihaowen@meizu.com>
To:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>
CC:     Haowen Bai <baihaowen@meizu.com>, <netdev@vger.kernel.org>,
        <bpf@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: [PATCH] libbpf: potential NULL dereference in usdt_manager_attach_usdt()
Date:   Thu, 7 Apr 2022 10:38:17 +0800
Message-ID: <1649299098-2069-1-git-send-email-baihaowen@meizu.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

link could be null but still dereference bpf_link__destroy(&link->link)
and it will lead to a null pointer access.

Signed-off-by: Haowen Bai <baihaowen@meizu.com>
---
 tools/lib/bpf/usdt.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/usdt.c b/tools/lib/bpf/usdt.c
index 1bce2eab5e89..b02ebc4ba57c 100644
--- a/tools/lib/bpf/usdt.c
+++ b/tools/lib/bpf/usdt.c
@@ -996,7 +996,7 @@ struct bpf_link *usdt_manager_attach_usdt(struct usdt_manager *man, const struct
 	link = calloc(1, sizeof(*link));
 	if (!link) {
 		err = -ENOMEM;
-		goto err_out;
+		goto link_err;
 	}
 
 	link->usdt_man = man;
@@ -1072,7 +1072,7 @@ struct bpf_link *usdt_manager_attach_usdt(struct usdt_manager *man, const struct
 
 err_out:
 	bpf_link__destroy(&link->link);
-
+link_err:
 	free(targets);
 	hashmap__free(specs_hash);
 	if (elf)
-- 
2.7.4