not all of the ICMP packets need an IP header payload, so we check the length
of the skbs only when the packets should have an IP header payload.

Based upon analysis and initial patch by Rodrigo Partearroyo González.
Signed-off-by: NChangli Gao <xiaosuo@gmail.com>
Acked-by: NHerbert Xu <herbert@gondor.apana.org.au>
----
 net/sched/act_nat.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
Signed-off-by: NDavid S. Miller <davem@davemloft.net>