Re: [PATCH bpf-next v4 00/20] bpf: Run exception cleanup landing pads when bpf_throw() unwinds

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

On Tue Sep 22, 2026 at 2:31 AM UTC, Kumar Kartikeya Dwivedi wrote:
>
> I think you misunderstood his question.
>
> What Eduard meant or is asking, was that (per his understanding), the verifier,
> in the future, would attempt to defer to runtime checks where it cannot prove
> certain patterns in the program safe, regardless of how they came to be (in C,
> or Rust). Instead of rejecting the program from loading, in such a case, we
> would emit some form of a runtime assertion that, for the remainder of the
> program, guarantees a given value to be in the range the verifier accepts, as a
> very simple example.
>
> In such a case, the assertion and associated panic is being injected after
> compilation, hence it is likely there is no associated landing pad to fall back
> to and clean up program resources. Yet to safety inject such a runtime assertion
> clean up would be necessary.

In this case presence of landing pads from rust is especially important.
The verifier would need to rely on them to insert additional run-time checks:
if something bad between [ip_start, ip_end] goto landing_pad.
It's not possible to insert control flow edge at random points,
since the verifier cannot see original rust code and its meaning.