[NETFILTER]: ip_tables: fix table locking in ipt_do_table

table->private might change because of ruleset changes, don't use it without
holding the lock.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/netfilter/ip_tables.c

@@ -230,7 +230,7 @@ ipt_do_table(struct sk_buff **pskb,
 	const char *indev, *outdev;
 	void *table_base;
 	struct ipt_entry *e, *back;
-	struct xt_table_info *private = table->private;
+	struct xt_table_info *private;
 
 	/* Initialization */
 	ip = (*pskb)->nh.iph;
@@ -247,6 +247,7 @@ ipt_do_table(struct sk_buff **pskb,
 
 	read_lock_bh(&table->lock);
 	IP_NF_ASSERT(table->valid_hooks & (1 << hook));
+	private = table->private;
 	table_base = (void *)private->entries[smp_processor_id()];
 	e = get_entry(table_base, private->hook_entry[hook]);