selftests/bpf: Test BTF walk into a flexible array of zero-sized elements

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The program stashes a bpf_obj_new() object whose type ends with a flexible
array of empty structs, then reads it back as an untrusted kptr. Without
the previous patch this divides by zero in btf_struct_walk() instead of
being rejected.

  # ./test_progs -t verifier_btf_flex_array
  ...
  #602     verifier_btf_flex_array:OK
  Summary: 1/1 PASSED, 0 SKIPPED, 0/0 FAILED

Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Link: https://lore.kernel.org/r/20260910122316.186384-2-jiayuan.chen@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

...

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Jiayuan Chen 2026-09-10 20:22:56 +08:00 • committed by Alexei Starovoitov

parent b0b3dc6652

commit f77d212457

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tools/testing/selftests/bpf/prog_tests/verifier.c

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56

tools/testing/selftests/bpf/progs/verifier_btf_flex_array.c

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