netfilter: nf_tables: fix userdata memleak

When userdata was introduced for tables and objects its allocation was
only freed inside the error path of the new{table, object} functions.

Free user data inside corresponding destroy functions for tables and
objects.

Fixes: b131c964 ("netfilter: nf_tables: add userdata support for nft_object")
Fixes: 7a81575b ("netfilter: nf_tables: add userdata attributes to nft_table")
Signed-off-by: Jose M. Guisado Gomez <guigom@riseup.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_api.c

@@ -1211,6 +1211,7 @@ static void nf_tables_table_destroy(struct nft_ctx *ctx)
 
 	rhltable_destroy(&ctx->table->chains_ht);
 	kfree(ctx->table->name);
+	kfree(ctx->table->udata);
 	kfree(ctx->table);
 }
 
@@ -6231,6 +6232,7 @@ static void nft_obj_destroy(const struct nft_ctx *ctx, struct nft_object *obj)
 
 	module_put(obj->ops->type->owner);
 	kfree(obj->key.name);
+	kfree(obj->udata);
 	kfree(obj);
 }