[PATCH v2] libbpf: Fix null pointer dereference in btf_dump__free on allocation failure

[PATCH v2] libbpf: Fix null pointer dereference in btf_dump__free on allocation failure

[chenyuan]

From: chenyuan <chenyuan@kylinos.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@kylinos.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

Re: [PATCH v2] libbpf: Fix null pointer dereference in btf_dump__free on allocation failure

[patchwork-bot+netdevbpf]

Hello:

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

On Wed, 18 Jun 2025 09:19:33 +0800 you wrote:
> From: chenyuan <chenyuan@kylinos.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.
> 
> [...]

Here is the summary with links:
  - [v2] libbpf: Fix null pointer dereference in btf_dump__free on allocation failure
    https://git.kernel.org/bpf/bpf/c/aa485e8789d5

You are awesome, thank you!
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