On Tue, 2020-08-04 at 21:25 +0200, Matthieu Baerts wrote:
> Hi Paolo,
>
> On 04/08/2020 18:31, Paolo Abeni wrote:
> > Nicolas reported the following oops:
>
> (...)
>
> > on some unconventional configuration.
> >
> > The MPTCP protocol is trying to create a subflow for an
> > unaccepted server socket. That is allowed by the RFC, even
> > if subflow creation will likely fail.
> > Unaccepted sockets have still a NULL sk_socket field,
> > avoid the issue by failing earlier.
> >
> > Reported-and-tested-by: Nicolas Rybowski <nicolas.rybow...@tessares.net>
> > Fixes: 7d14b0d2b9b3 ("mptcp: set correct vfs info for subflows")
>
> Thank you for the patch, the addition in the code looks very good to me!
>
> But are you sure the commit you mention introduces the issue you fix here?
AFAICS, the oops can be observed only with the mentioned commit - which
unconditioanlly de-reference a NULL sk->sk_socket. [try to] create a
subflow on server unaccepted socket is not a bug per-se, so I would not
send the fix to older trees.
Thanks,
Paolo
