dns_resolver: assure that dns_query() result is null-terminated

dns_query() credulously assumes that keys are null-terminated and
returns a copy of a memory block that is off by one.

Signed-off-by: Manuel Schölling <manuel.schoelling@gmx.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc net/dns_resolver/dns_query.c
Simple merge