netfilter: nf_tables: Carry s_idx in nft_obj_dump_ctx

Prep work for moving the context into struct netlink_callback scratch
area.
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_api.c

@@ -7682,6 +7682,7 @@ static void audit_log_obj_reset(const struct nft_table *table,
 }
 
 struct nft_obj_dump_ctx {
+	unsigned int	s_idx;
 	char		*table;
 	u32		type;
 };
@@ -7689,14 +7690,14 @@ struct nft_obj_dump_ctx {
 static int nf_tables_dump_obj(struct sk_buff *skb, struct netlink_callback *cb)
 {
 	const struct nfgenmsg *nfmsg = nlmsg_data(cb->nlh);
-	const struct nft_table *table;
-	unsigned int idx = 0, s_idx = cb->args[0];
 	struct nft_obj_dump_ctx *ctx = cb->data;
 	struct net *net = sock_net(skb->sk);
 	int family = nfmsg->nfgen_family;
 	struct nftables_pernet *nft_net;
+	const struct nft_table *table;
 	unsigned int entries = 0;
 	struct nft_object *obj;
+	unsigned int idx = 0;
 	bool reset = false;
 	int rc = 0;
 
@@ -7715,7 +7716,7 @@ static int nf_tables_dump_obj(struct sk_buff *skb, struct netlink_callback *cb)
 		list_for_each_entry_rcu(obj, &table->objects, list) {
 			if (!nft_is_active(net, obj))
 				goto cont;
-			if (idx < s_idx)
+			if (idx < ctx->s_idx)
 				goto cont;
 			if (ctx->table && strcmp(ctx->table, table->name))
 				goto cont;
@@ -7745,7 +7746,7 @@ static int nf_tables_dump_obj(struct sk_buff *skb, struct netlink_callback *cb)
 	}
 	rcu_read_unlock();
 
-	cb->args[0] = idx;
+	ctx->s_idx = idx;
 	return skb->len;
 }