Re: [syzbot] [mptcp?] KMSAN: uninit-value in mptcp_established_options

[Matthieu Baerts <matttbe@kernel.org>]

Hi Alexander,

On 12/05/2026 11:31, Alexander Potapenko wrote:
>>>>>> Plus I'm not exactly sure to understand the issue here: mp_opt is
>>>>>> defined and used only in mptcp_incoming_options(), and I don't see
>>>>>> anything using it after the end of this function. Or did I miss something?
>>>>>
>>>>> I also had hard time understanding the backtrace, I think some frames
>>>>> are omitted/missing (it happens sometime, IDK why), specifically the one
>>>>> related to mptcp_options_received() - which would be useful to
>>>>> understand the issue.
>>>>
>>>> This is probably related to
>>>> https://lore.kernel.org/all/69e7ee1f.a00a0220.17a17.001d.GAE@google.com/T/
>>>
>>> Ah yes, it looks similar.
>>>
>>>> Let me send the patch, perhaps this issue will also go away.
>>>
>>> That would be great, thank you!
>>
>> Thank you for having sent your patch.
>>
>> Here is one combining your modifications, and the ones from Paolo, for
>> syzbot. If this one is OK, we can continue with Paolo's patch.
> 
> 
> Hi Matt,
> 
> Unfortunately my approach was wrong: see tglx's response there.
> Hope we'll figure something out (__no_kmsan_checks looks promising)
Thank you for your reply, I just found the email thread you mentioned:

  https://lore.kernel.org/all/87v7cu876c.ffs@tglx

If a v2 is not expected "soon", I'm sure we can continue with Paolo's
patch, and double-check later to see if it was enough.

Cheers,
Matt
-- 
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