Re: [PATCH net-next 2/2] inet: Fix get port to handle zero port number with soreuseport set

On Wed, Dec 14, 2016 at 7:54 PM, Tom Herbert [off-list ref] wrote:

A user may call listen with binding an explicit port with the intent
that the kernel will assign an available port to the socket. In this
case inet_csk_get_port does a port scan. For such sockets, the user may
also set soreuseport with the intent a creating more sockets for the
port that is selected. The problem is that the initial socket being
opened could inadvertently choose an existing and unreleated port
number that was already created with soreuseport.

Good catch!  I think this problem may also exist in the UDP path?
(udp_lib_get_port -> udp_lib_lport_inuse[2])