Re: [PATCH bpf-next v1 1/3] bpf: Validate graph ownership with a bounded walk

["Alexei Starovoitov" <alexei.starovoitov@gmail.com>]

On Sat Sep 5, 2026 at 2:07 AM PDT, Kumar Kartikeya Dwivedi wrote:
> btf_check_and_fixup_fields() prevents graph ownership cycles with a
> one-hop restriction: a type that contains both a graph root and node cannot
> own another root type. This limits graph ownership chains to three types,
> but also rejects longer acyclic relationships.
>
> All struct metadata is available once field fixups finish. Move ownership
> validation out of the per-record fixup helper and walk graph-root type
> relationships directly at BTF load time. Reject cycles and chains deeper
> than eight record-bearing types, which keeps recursive destruction bounded
> while permitting safe acyclic layouts.
>
> Keep the depth limit independent of MAX_CALL_FRAMES because graph teardown
> can run beneath a BPF call chain. btf_check_and_fixup_fields() continues to
> initialize graph_root.value_rec, including for the separately allocated map
> record. The ownership relationship itself belongs to the immutable BTF and
> therefore only needs validation once during BTF load.
>
> Update the graph BTF tests to accept the two acyclic relationships that the
> old approximation rejected.

Are you saying old approximation was not correct?
Pls explain how it missed it.

Probably better to merge patch 1 and 2. I don't see why they're split like that
and patch 2 immediately fixes patch 1.

pw-bot: cr