netfilter: nf_tables: limit maximum table name length to 32 bytes

Set the same as we use for chain names, it should be enough.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_tables.h

@@ -535,7 +535,7 @@ struct nft_table {
 	u64				hgenerator;
 	u32				use;
 	u16				flags;
-	char				name[];
+	char				name[NFT_TABLE_MAXNAMELEN];
 };
 
 /**

include/uapi/linux/netfilter/nf_tables.h

 #ifndef _LINUX_NF_TABLES_H
 #define _LINUX_NF_TABLES_H
 
+#define NFT_TABLE_MAXNAMELEN	32
 #define NFT_CHAIN_MAXNAMELEN	32
 #define NFT_USERDATA_MAXLEN	256
 

net/netfilter/nf_tables_api.c

@@ -401,7 +401,8 @@ nf_tables_chain_type_lookup(const struct nft_af_info *afi,
 }
 
 static const struct nla_policy nft_table_policy[NFTA_TABLE_MAX + 1] = {
-	[NFTA_TABLE_NAME]	= { .type = NLA_STRING },
+	[NFTA_TABLE_NAME]	= { .type = NLA_STRING,
+				    .len = NFT_TABLE_MAXNAMELEN - 1 },
 	[NFTA_TABLE_FLAGS]	= { .type = NLA_U32 },
 };
 
@@ -686,13 +687,13 @@ static int nf_tables_newtable(struct sock *nlsk, struct sk_buff *skb,
 	if (!try_module_get(afi->owner))
 		return -EAFNOSUPPORT;
 
-	table = kzalloc(sizeof(*table) + nla_len(name), GFP_KERNEL);
+	table = kzalloc(sizeof(*table), GFP_KERNEL);
 	if (table == NULL) {
 		module_put(afi->owner);
 		return -ENOMEM;
 	}
 
-	nla_strlcpy(table->name, name, nla_len(name));
+	nla_strlcpy(table->name, name, NFT_TABLE_MAXNAMELEN);
 	INIT_LIST_HEAD(&table->chains);
 	INIT_LIST_HEAD(&table->sets);
 	table->flags = flags;