1 files changed, 1 insertions, 0 deletions

diff --git a/net/ipv4/netfilter/ip_conntrack_proto_tcp.c b/net/ipv4/netfilter/ip_conntrack_proto_tcp.c
index 2b87c1974be6..721ddbf522b4 100644
--- a/net/ipv4/netfilter/ip_conntrack_proto_tcp.c
+++ b/net/ipv4/netfilter/ip_conntrack_proto_tcp.c
@@ -819,6 +819,7 @@ static int tcp_error(struct sk_buff *skb,
          */
         /* FIXME: Source route IP option packets --RR */
         if (hooknum == NF_IP_PRE_ROUTING
+            && skb->ip_summed != CHECKSUM_UNNECESSARY
             && csum_tcpudp_magic(iph->saddr, iph->daddr, tcplen, IPPROTO_TCP,
                                  skb->ip_summed == CHECKSUM_HW ? skb->csum
                                  : skb_checksum(skb, iph->ihl*4, tcplen, 0))) {