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

[Matthieu Baerts <matttbe@kernel.org>]

On 09/07/2026 15:12, Michael Bommarito wrote:
> On Thu, Jul 9, 2026 at 8:27 AM Matthieu Baerts <matttbe@kernel.org> 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.

Interesting. Yes, it could be useful for various protocols.

> 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.

Is it also based on crafted traffic? It could also be useful!

>> 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!

Cheers,
Matt
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