In the Linux kernel, the following vulnerability has been resolved:
nvmet-tcp: fixup hang in nvmet_tcp_listen_data_ready()
When the socket is closed while in TCP_LISTEN a callback is run to
flush all outstanding packets, which in turns calls
nvmet_tcp_listen_data_ready() with the sk_callback_lock held.
So we need to check if we are in TCP_LISTEN before attempting
to get the sk_callback_lock() to avoid a deadlock.
