On Thu, 12 Dec 2019 22:35:58 +0100, Karsten Graul wrote:
> From: Ursula Braun <ubraun@xxxxxxxxxxxxx>
>
> FASTOPEN setsockopt() or sendmsg() may switch the SMC socket to fallback
> mode. Once fallback mode is active, the native TCP socket functions are
> called. Nevertheless there is a small race window, when FASTOPEN
> setsockopt/sendmsg runs in parallel to a connect(), and switch the
> socket into fallback mode before connect() takes the sock lock.
> Make sure the SMC-specific connect setup is omitted in this case.
>
> This way a syzbot-reported refcount problem is fixed, triggered by
> different threads running non-blocking connect() and FASTOPEN_KEY
> setsockopt.
>
> Reported-by: syzbot+96d3f9ff6a86d37e44c8@xxxxxxxxxxxxxxxxxxxxxxxxx
> Fixes: 6d6dd528d5af ("net/smc: fix refcount non-blocking connect() -part 2")
> Signed-off-by: Ursula Braun <ubraun@xxxxxxxxxxxxx>
> Signed-off-by: Karsten Graul <kgraul@xxxxxxxxxxxxx>
Applied, and queued for stable, thank you!
