diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h
index c2ee5d8..c00cc0c 100644
--- a/include/linux/netfilter/x_tables.h
+++ b/include/linux/netfilter/x_tables.h
@@ -333,7 +333,7 @@
 	/* Called when user tries to insert an entry of this type:
            hook_mask is a bitmask of hooks from which it can be
            called. */
-	/* Should return true or false, or an error code (-Exxxx). */
+	/* Should return 0 on success or an error code otherwise (-Exxxx). */
 	int (*checkentry)(const struct xt_tgchk_param *);
 
 	/* Called when entry of this type deleted. */
diff --git a/include/net/netfilter/nf_conntrack_core.h b/include/net/netfilter/nf_conntrack_core.h
index dffde8e..3d7524f 100644
--- a/include/net/netfilter/nf_conntrack_core.h
+++ b/include/net/netfilter/nf_conntrack_core.h
@@ -61,7 +61,7 @@
 	int ret = NF_ACCEPT;
 
 	if (ct && ct != &nf_conntrack_untracked) {
-		if (!nf_ct_is_confirmed(ct) && !nf_ct_is_dying(ct))
+		if (!nf_ct_is_confirmed(ct))
 			ret = __nf_conntrack_confirm(skb);
 		if (likely(ret == NF_ACCEPT))
 			nf_ct_deliver_cached_events(ct);
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index b83c530..eeeb8bc 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -424,6 +424,16 @@
 
 	spin_lock_bh(&nf_conntrack_lock);
 
+	/* We have to check the DYING flag inside the lock to prevent
+	   a race against nf_ct_get_next_corpse() possibly called from
+	   user context, else we insert an already 'dead' hash, blocking
+	   further use of that particular connection -JM */
+
+	if (unlikely(nf_ct_is_dying(ct))) {
+		spin_unlock_bh(&nf_conntrack_lock);
+		return NF_ACCEPT;
+	}
+
 	/* See if there's one in the list already, including reverse:
 	   NAT could have grabbed it without realizing, since we're
 	   not in the hash.  If there is, we lost race. */
diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
index b20f427..53d8922 100644
--- a/net/netfilter/nf_conntrack_sip.c
+++ b/net/netfilter/nf_conntrack_sip.c
@@ -1393,10 +1393,8 @@
 
 	nf_ct_refresh(ct, skb, sip_timeout * HZ);
 
-	if (skb_is_nonlinear(skb)) {
-		pr_debug("Copy of skbuff not supported yet.\n");
-		return NF_ACCEPT;
-	}
+	if (unlikely(skb_linearize(skb)))
+		return NF_DROP;
 
 	dptr = skb->data + dataoff;
 	datalen = skb->len - dataoff;
@@ -1455,10 +1453,8 @@
 
 	nf_ct_refresh(ct, skb, sip_timeout * HZ);
 
-	if (skb_is_nonlinear(skb)) {
-		pr_debug("Copy of skbuff not supported yet.\n");
-		return NF_ACCEPT;
-	}
+	if (unlikely(skb_linearize(skb)))
+		return NF_DROP;
 
 	dptr = skb->data + dataoff;
 	datalen = skb->len - dataoff;