Re: [PATCH v2] mptcp: only set DATA_FIN when a mapping is present

[Michael Bommarito]

On Thu, Jul 9, 2026 at 8:27 AM Matthieu Baerts <matttbe@xxxxxxxxxx> wrote:

> By chance, do you have a reproducer? Maybe using Packetdrill with MPTCP
> support? [1]
> If not, how did you discover this issue?

Yup, I'll send to you offlist.  It's a custom Python/TUN/qemu setup,
not Packetdrill, but I'm guessing it could be ported or extended for
testing/fuzzing.

I discovered it with my homegrown agentic stack, which is a Rube
Goldberg machine full of various tools (like cocci, semgrep) and
knowledge graphs (built with libclang).  The agent logs suggest that
it came from a family of rules that surfaces suspicious struct init
candidates, which I can share too.

> If I may add, please also send new version in a separate thread, not as
> a reply, not to confuse various tools, as mentioned in the same doc.

Sure, thanks to both you and Gang for the feedback.  I'll send a v3
based on your suggestions later today.

Thanks,
Mike