tipc: fix an infoleak in tipc_nl_compat_link_dump

link_info.str is a char array of size 60. Memory after the NULL
byte is not initialized. Sending the whole object out can cause
a leak.

Signed-off-by: Kangjie Lu <kjlu@gatech.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 5d2be142)
CVE-2016-5243
BugLink: https://bugs.launchpad.net/bugs/1589036


Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>