[PATCH bpf v2 1/2] libbpf: Fix array comparison in BTF dedup

[Mingpei CAO <caomingpei@gmail.com>]

btf_dedup_identical_types() reads both array descriptors from t1,
skipping comparisons of their referenced types. This can incorrectly
merge distinct structs and corrupt CO-RE relocation metadata.

Read the second descriptor from t2.

Fixes: 62e23f183839 ("libbpf: Improve BTF dedup handling of "identical" BTF types")
Closes: https://lore.kernel.org/bpf/CABzjXVz3iBuump-pXFkefZ5v+2uu4fG61zqRyWD4xmz3PuBycw@mail.gmail.com/
Assisted-by: LLM
Signed-off-by: Mingpei CAO <caomingpei@gmail.com>
---
 tools/lib/bpf/btf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 8417de92d028..41cc3140925f 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -4827,7 +4827,7 @@ static bool btf_dedup_identical_types(struct btf_dedup *d, __u32 id1, __u32 id2,
 			return false;
 
 		a1 = btf_array(t1);
-		a2 = btf_array(t1);
+		a2 = btf_array(t2);
 
 		if (a1->index_type != a2->index_type &&
 		    !btf_dedup_identical_types(d, a1->index_type, a2->index_type, depth - 1))
-- 
2.43.0