netfilter: nf_tables: Fix a memory leak in nf_tables_updchain

If nft_netdev_register_hooks() fails, the memory associated with
nft_stats is not freed, causing a memory leak.

This patch fixes it by moving nft_stats_alloc() down after
nft_netdev_register_hooks() succeeds.

Fixes: b9703ed4 ("netfilter: nf_tables: support for adding new devices to an existing netdev chain")
Signed-off-by: Quan Tian <tianquan23@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_api.c

@@ -2631,19 +2631,6 @@ static int nf_tables_updchain(struct nft_ctx *ctx, u8 genmask, u8 policy,
 		}
 	}
 
-	if (nla[NFTA_CHAIN_COUNTERS]) {
-		if (!nft_is_base_chain(chain)) {
-			err = -EOPNOTSUPP;
-			goto err_hooks;
-		}
-
-		stats = nft_stats_alloc(nla[NFTA_CHAIN_COUNTERS]);
-		if (IS_ERR(stats)) {
-			err = PTR_ERR(stats);
-			goto err_hooks;
-		}
-	}
-
 	if (!(table->flags & NFT_TABLE_F_DORMANT) &&
 	    nft_is_base_chain(chain) &&
 	    !list_empty(&hook.list)) {
@@ -2658,6 +2645,20 @@ static int nf_tables_updchain(struct nft_ctx *ctx, u8 genmask, u8 policy,
 	}
 
 	unregister = true;
+
+	if (nla[NFTA_CHAIN_COUNTERS]) {
+		if (!nft_is_base_chain(chain)) {
+			err = -EOPNOTSUPP;
+			goto err_hooks;
+		}
+
+		stats = nft_stats_alloc(nla[NFTA_CHAIN_COUNTERS]);
+		if (IS_ERR(stats)) {
+			err = PTR_ERR(stats);
+			goto err_hooks;
+		}
+	}
+
 	err = -ENOMEM;
 	trans = nft_trans_alloc(ctx, NFT_MSG_NEWCHAIN,
 				sizeof(struct nft_trans_chain));