diff --git a/include/net/netfilter/nf_conntrack_timeout.h b/include/net/netfilter/nf_conntrack_timeout.h
index 62308713dd7f..f72be38860a7 100644
--- a/include/net/netfilter/nf_conntrack_timeout.h
+++ b/include/net/netfilter/nf_conntrack_timeout.h
@@ -20,10 +20,20 @@ struct ctnl_timeout {
 };
 
 struct nf_conn_timeout {
-	struct ctnl_timeout	*timeout;
+	struct ctnl_timeout __rcu *timeout;
 };
 
-#define NF_CT_TIMEOUT_EXT_DATA(__t) (unsigned int *) &((__t)->timeout->data)
+static inline unsigned int *
+nf_ct_timeout_data(struct nf_conn_timeout *t)
+{
+	struct ctnl_timeout *timeout;
+
+	timeout = rcu_dereference(t->timeout);
+	if (timeout == NULL)
+		return NULL;
+
+	return (unsigned int *)timeout->data;
+}
 
 static inline
 struct nf_conn_timeout *nf_ct_timeout_find(const struct nf_conn *ct)
@@ -47,7 +57,7 @@ struct nf_conn_timeout *nf_ct_timeout_ext_add(struct nf_conn *ct,
 	if (timeout_ext == NULL)
 		return NULL;
 
-	timeout_ext->timeout = timeout;
+	rcu_assign_pointer(timeout_ext->timeout, timeout);
 
 	return timeout_ext;
 #else
@@ -64,10 +74,13 @@ nf_ct_timeout_lookup(struct net *net, struct nf_conn *ct,
 	unsigned int *timeouts;
 
 	timeout_ext = nf_ct_timeout_find(ct);
-	if (timeout_ext)
-		timeouts = NF_CT_TIMEOUT_EXT_DATA(timeout_ext);
-	else
+	if (timeout_ext) {
+		timeouts = nf_ct_timeout_data(timeout_ext);
+		if (unlikely(!timeouts))
+			timeouts = l4proto->get_timeouts(net);
+	} else {
 		timeouts = l4proto->get_timeouts(net);
+	}
 
 	return timeouts;
 #else
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 09d1d19b2ab9..3cb3cb831591 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -940,10 +940,13 @@ init_conntrack(struct net *net, struct nf_conn *tmpl,
 	}
 
 	timeout_ext = tmpl ? nf_ct_timeout_find(tmpl) : NULL;
-	if (timeout_ext)
-		timeouts = NF_CT_TIMEOUT_EXT_DATA(timeout_ext);
-	else
+	if (timeout_ext) {
+		timeouts = nf_ct_timeout_data(timeout_ext);
+		if (unlikely(!timeouts))
+			timeouts = l4proto->get_timeouts(net);
+	} else {
 		timeouts = l4proto->get_timeouts(net);
+	}
 
 	if (!l4proto->new(ct, skb, dataoff, timeouts)) {
 		nf_conntrack_free(ct);
@@ -952,7 +955,8 @@ init_conntrack(struct net *net, struct nf_conn *tmpl,
 	}
 
 	if (timeout_ext)
-		nf_ct_timeout_ext_add(ct, timeout_ext->timeout, GFP_ATOMIC);
+		nf_ct_timeout_ext_add(ct, rcu_dereference(timeout_ext->timeout),
+				      GFP_ATOMIC);
 
 	nf_ct_acct_ext_add(ct, GFP_ATOMIC);
 	nf_ct_tstamp_ext_add(ct, GFP_ATOMIC);
diff --git a/net/netfilter/nfnetlink_cttimeout.c b/net/netfilter/nfnetlink_cttimeout.c
index 476accd17145..5bda647d8a80 100644
--- a/net/netfilter/nfnetlink_cttimeout.c
+++ b/net/netfilter/nfnetlink_cttimeout.c
@@ -291,6 +291,34 @@ cttimeout_get_timeout(struct sock *ctnl, struct sk_buff *skb,
 	return ret;
 }
 
+static void untimeout(struct nf_conntrack_tuple_hash *i,
+		      struct ctnl_timeout *timeout)
+{
+	struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i);
+	struct nf_conn_timeout *timeout_ext = nf_ct_timeout_find(ct);
+
+	if (timeout_ext && (!timeout || timeout_ext->timeout == timeout))
+		RCU_INIT_POINTER(timeout_ext->timeout, NULL);
+}
+
+static void ctnl_untimeout(struct ctnl_timeout *timeout)
+{
+	struct nf_conntrack_tuple_hash *h;
+	const struct hlist_nulls_node *nn;
+	int i;
+
+	local_bh_disable();
+	for (i = 0; i < init_net.ct.htable_size; i++) {
+		spin_lock(&nf_conntrack_locks[i % CONNTRACK_LOCKS]);
+		if (i < init_net.ct.htable_size) {
+			hlist_nulls_for_each_entry(h, nn, &init_net.ct.hash[i], hnnode)
+				untimeout(h, timeout);
+		}
+		spin_unlock(&nf_conntrack_locks[i % CONNTRACK_LOCKS]);
+	}
+	local_bh_enable();
+}
+
 /* try to delete object, fail if it is still in use. */
 static int ctnl_timeout_try_del(struct ctnl_timeout *timeout)
 {
@@ -301,6 +329,7 @@ static int ctnl_timeout_try_del(struct ctnl_timeout *timeout)
 		/* We are protected by nfnl mutex. */
 		list_del_rcu(&timeout->head);
 		nf_ct_l4proto_put(timeout->l4proto);
+		ctnl_untimeout(timeout);
 		kfree_rcu(timeout, rcu_head);
 	} else {
 		/* still in use, restore reference counter. */
@@ -567,6 +596,10 @@ static void __exit cttimeout_exit(void)
 	pr_info("cttimeout: unregistering from nfnetlink.\n");
 
 	nfnetlink_subsys_unregister(&cttimeout_subsys);
+
+	/* Make sure no conntrack objects refer to custom timeouts anymore. */
+	ctnl_untimeout(NULL);
+
 	list_for_each_entry_safe(cur, tmp, &cttimeout_list, head) {
 		list_del_rcu(&cur->head);
 		/* We are sure that our objects have no clients at this point,
diff --git a/net/netfilter/xt_CT.c b/net/netfilter/xt_CT.c
index a03924c1db41..e7ac07e53b59 100644
--- a/net/netfilter/xt_CT.c
+++ b/net/netfilter/xt_CT.c
@@ -321,8 +321,10 @@ static void xt_ct_destroy_timeout(struct nf_conn *ct)
 
 	if (timeout_put) {
 		timeout_ext = nf_ct_timeout_find(ct);
-		if (timeout_ext)
+		if (timeout_ext) {
 			timeout_put(timeout_ext->timeout);
+			RCU_INIT_POINTER(timeout_ext->timeout, NULL);
+		}
 	}
 	rcu_read_unlock();
 #endif