[PATCH bpf v2 0/2] libbpf: Fix array comparison in BTF dedup

[Mingpei CAO <caomingpei@gmail.com>]

The recursive array comparison in BTF dedup reads both descriptors from
the first type. This can merge distinct structures and corrupt CO-RE
relocation metadata. Fix the comparison and add three regression cases to
the existing BTF dedup tests.

Changes in v2:
- Move the tests into prog_tests/btf.c using Alan Maguire's two cases.
- Add a separate negative case with the same index type to isolate
  element-type comparison.
- Keep patch 1 unchanged.

v1: https://lore.kernel.org/bpf/20260907131021.34343-1-caomingpei@gmail.com/
Report: https://lore.kernel.org/bpf/CABzjXVz3iBuump-pXFkefZ5v+2uu4fG61zqRyWD4xmz3PuBycw@mail.gmail.com/

Validation with a focused runner using the existing selftest sources and
assertions:
- 52 existing BTF cases passed before and after the fix.
- Both negative cases failed before the fix and passed afterwards.
- The positive case passed before and after the fix.

Mingpei CAO (2):
  libbpf: Fix array comparison in BTF dedup
  selftests/bpf: Test array element comparison in BTF dedup

 tools/lib/bpf/btf.c                          |   2 +-
 tools/testing/selftests/bpf/prog_tests/btf.c | 126 +++++++++++++++++++
 2 files changed, 127 insertions(+), 1 deletion(-)


base-commit: df2908090cda368b01ff43709f51890076c56157
-- 
2.43.0