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

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Message-ID: <CAEfhGixrj8Ftwo8=F617o-ArwgCD+JmVUeJpNbU7xpydp=pjBA@mail.gmail.com>
Date:   Thu, 15 Dec 2016 10:58:29 -0500
From:   Craig Gallek <kraigatgoog@...il.com>
To:     Tom Herbert <tom@...bertland.com>
Cc:     David Miller <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>, kernel-team@...com,
        Josef Bacik <jbacik@...com>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: 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 <tom@...bertland.com> 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])