diff --git a/net/netfilter/nf_conntrack_proto_dccp.c b/net/netfilter/nf_conntrack_proto_dccp.c
index 3ba1f4d9934fbf3a093a87d783743b6cd124f723..cd7a51a0f10079cd8eab6841843379d3fa9d40b0 100644
--- a/net/netfilter/nf_conntrack_proto_dccp.c
+++ b/net/netfilter/nf_conntrack_proto_dccp.c
@@ -433,17 +433,47 @@ static u64 dccp_ack_seq(const struct dccp_hdr *dh)
 		     ntohl(dhack->dccph_ack_nr_low);
 }
 
+struct nf_conntrack_dccp_buf {
+	struct dccp_hdr dh;	 /* generic header part */
+	struct dccp_hdr_ext ext; /* optional depending dh->dccph_x */
+	union {			 /* depends on header type */
+		struct dccp_hdr_ack_bits ack;
+		struct dccp_hdr_request req;
+		struct dccp_hdr_response response;
+		struct dccp_hdr_reset rst;
+	} u;
+};
+
+static struct dccp_hdr *
+dccp_header_pointer(const struct sk_buff *skb, int offset, const struct dccp_hdr *dh,
+		    struct nf_conntrack_dccp_buf *buf)
+{
+	unsigned int hdrlen = __dccp_hdr_len(dh);
+
+	if (hdrlen > sizeof(*buf))
+		return NULL;
+
+	return skb_header_pointer(skb, offset, hdrlen, buf);
+}
+
 static int dccp_packet(struct nf_conn *ct, const struct sk_buff *skb,
 		       unsigned int dataoff, enum ip_conntrack_info ctinfo)
 {
 	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
-	struct dccp_hdr _dh, *dh;
+	struct nf_conntrack_dccp_buf _dh;
 	u_int8_t type, old_state, new_state;
 	enum ct_dccp_roles role;
 	unsigned int *timeouts;
+	struct dccp_hdr *dh;
 
 	dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &_dh);
 	BUG_ON(dh == NULL);
+
+	/* pull again, including possible 48 bit sequences and subtype header */
+	dh = dccp_header_pointer(skb, dataoff, dh, &_dh);
+	if (!dh)
+		return NF_DROP;
+
 	type = dh->dccph_type;
 
 	if (type == DCCP_PKT_RESET &&
@@ -526,10 +556,20 @@ static int dccp_error(struct net *net, struct nf_conn *tmpl,
 		      struct sk_buff *skb, unsigned int dataoff,
 		      u_int8_t pf, unsigned int hooknum)
 {
+	static const unsigned long require_seq48 = 1 << DCCP_PKT_REQUEST |
+						   1 << DCCP_PKT_RESPONSE |
+						   1 << DCCP_PKT_CLOSEREQ |
+						   1 << DCCP_PKT_CLOSE |
+						   1 << DCCP_PKT_RESET |
+						   1 << DCCP_PKT_SYNC |
+						   1 << DCCP_PKT_SYNCACK;
 	struct dccp_hdr _dh, *dh;
 	unsigned int dccp_len = skb->len - dataoff;
 	unsigned int cscov;
 	const char *msg;
+	u8 type;
+
+	BUILD_BUG_ON(DCCP_PKT_INVALID >= BITS_PER_LONG);
 
 	dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &_dh);
 	if (dh == NULL) {
@@ -559,11 +599,17 @@ static int dccp_error(struct net *net, struct nf_conn *tmpl,
 		goto out_invalid;
 	}
 
-	if (dh->dccph_type >= DCCP_PKT_INVALID) {
+	type = dh->dccph_type;
+	if (type >= DCCP_PKT_INVALID) {
 		msg = "nf_ct_dccp: reserved packet type ";
 		goto out_invalid;
 	}
 
+	if (test_bit(type, &require_seq48) && !dh->dccph_x) {
+		msg = "nf_ct_dccp: type lacks 48bit sequence numbers";
+		goto out_invalid;
+	}
+
 	return NF_ACCEPT;
 
 out_invalid: