linux-kernel - [PATCH v2] libbpf: Fix null pointer dereference in btf_dump_

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Message-Id: <20250618011933.11423-1-chenyuan_fl@163.com>
Date: Wed, 18 Jun 2025 09:19:33 +0800
From: chenyuan <chenyuan_fl@....com>
To: ast@...nel.org
Cc: andrii.nakryiko@...il.com,
	bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	chenyuan_fl@....com,
	chenyuan <chenyuan@...inos.cn>
Subject: [PATCH v2] libbpf: Fix null pointer dereference in btf_dump__free on allocation failure

From: chenyuan <chenyuan@...inos.cn>

When btf_dump__new() fails to allocate memory for the internal hashmap
(btf_dump->type_names), it returns an error code. However, the cleanup
function btf_dump__free() does not check if btf_dump->type_names is NULL
before attempting to free it. This leads to a null pointer dereference
when btf_dump__free() is called on a btf_dump object.

Fix: 351131b51c7a ("libbpf: add btf_dump API for BTF-to-C conversion")
Signed-off-by: chenyuan <chenyuan@...inos.cn>
---
 tools/lib/bpf/btf_dump.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index 7c2f1f13f958..f09f25eccf3c 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -227,6 +227,9 @@ static void btf_dump_free_names(struct hashmap *map)
 	size_t bkt;
 	struct hashmap_entry *cur;
 
+	if (!map)
+		return;
+
 	hashmap__for_each_entry(map, cur, bkt)
 		free((void *)cur->pkey);
 
-- 
2.25.1