netfilter: xt_CT: missing rcu_read_lock section in timeout assignment

Fix a dereference to pointer without rcu_read_lock held.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/xt_CT.c

@@ -218,6 +218,7 @@ static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
 		struct ctnl_timeout *timeout;
 		struct nf_conn_timeout *timeout_ext;
 
+		rcu_read_lock();
 		timeout_find_get =
 			rcu_dereference(nf_ct_timeout_find_get_hook);
 
@@ -228,21 +229,21 @@ static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
 				ret = -EINVAL;
 				pr_info("You cannot use inversion on "
 					 "L4 protocol\n");
-				goto err3;
+				goto err4;
 			}
 			timeout = timeout_find_get(info->timeout);
 			if (timeout == NULL) {
 				ret = -ENOENT;
 				pr_info("No such timeout policy \"%s\"\n",
 					info->timeout);
-				goto err3;
+				goto err4;
 			}
 			if (timeout->l3num != par->family) {
 				ret = -EINVAL;
 				pr_info("Timeout policy `%s' can only be "
 					"used by L3 protocol number %d\n",
 					info->timeout, timeout->l3num);
-				goto err3;
+				goto err4;
 			}
 			if (timeout->l4proto->l4proto != e->ip.proto) {
 				ret = -EINVAL;
@@ -250,19 +251,20 @@ static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
 					"used by L4 protocol number %d\n",
 					info->timeout,
 					timeout->l4proto->l4proto);
-				goto err3;
+				goto err4;
 			}
 			timeout_ext = nf_ct_timeout_ext_add(ct, timeout,
 							    GFP_KERNEL);
 			if (timeout_ext == NULL) {
 				ret = -ENOMEM;
-				goto err3;
+				goto err4;
 			}
 		} else {
 			ret = -ENOENT;
 			pr_info("Timeout policy base is empty\n");
-			goto err3;
+			goto err4;
 		}
+		rcu_read_unlock();
 	}
 #endif
 
@@ -272,6 +274,8 @@ static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
 	info->ct = ct;
 	return 0;
 
+err4:
+	rcu_read_unlock();
 err3:
 	nf_conntrack_free(ct);
 err2:
@@ -313,6 +317,7 @@ static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
 		nf_ct_l3proto_module_put(par->family);
 
 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
+		rcu_read_lock();
 		timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
 
 		if (timeout_put) {
@@ -320,6 +325,7 @@ static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
 			if (timeout_ext)
 				timeout_put(timeout_ext->timeout);
 		}
+		rcu_read_unlock();
 #endif
 	}
 	nf_ct_put(info->ct);