Re: [PATCH bpf-next] libbpf: avoid NULL deref when initializing map BTF info

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On 3/19/22 5:19 PM, Andrii Nakryiko wrote:
If BPF object doesn't have an BTF info, don't attempt to search for BTF
types describing BPF map key or value layout.

Fixes: 262cfb74ffda ("libbpf: Init btf_{key,value}_type_id on internal map open")
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>

So without this patch, we may have segfault or other errors, right?
It would be good to specify that in the commit message.

The code change looks good to me.

Acked-by: Yonghong Song <yhs@xxxxxx>

---
  tools/lib/bpf/libbpf.c | 3 +++
  1 file changed, 3 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 7526419e59e0..2efe9431c1ba 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4197,6 +4197,9 @@ static int bpf_map_find_btf_info(struct bpf_object *obj, struct bpf_map *map)
  	__u32 key_type_id = 0, value_type_id = 0;
  	int ret;
+ if (!obj->btf)
+		return -ENOENT;
+
  	/* if it's BTF-defined map, we don't need to search for type IDs.
  	 * For struct_ops map, it does not need btf_key_type_id and
  	 * btf_value_type_id.



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