Re: [PATCH net v4] net: pin protocol module before inet socket allocation

[Chengfeng Ye]

On Fri, Oct 9, 2026 at 7:49 AM Jakub Kicinski <kuba@xxxxxxxxxx> wrote:
>
> On Fri, 02 Oct 2026 17:44:13 +0000 netdev-bot+sinfo@xxxxxxxxxx wrote:
> > This is an automated message. This series looks like a fix, but its
> > commit messages seem to be missing some information:
> >
> >  - How the issue was discovered, e.g. hit in production, hit during
> >    development, syzbot report, manual code inspection, LLM or static
> >    analysis tool scan.
>
> You have to answer the bot's question.

An LLM-based scan of the networking source initially identified the
issue, I then reproduced it with l2tp_ip by racing socket (AF_INET,
SOCK_DGRAM, IPPROTO_L2TP) against module unload on a KASAN-enabled
kernel on QEMU.

The reproduction used a temporary 50 ms delay between reading
prot->slab and calling kmem_cache_alloc() to widen the reported window
proto_unregister() destroyed the same cache before the allocation used
it.

Best regards,
Chengfeng