netfilter: nf_tables_offload: unbind if multi-device binding fails

nft_flow_block_chain() needs to unbind in case of error when performing
the multi-device binding.

Fixes: d54725cd ("netfilter: nf_tables: support for multiple devices per netdev hook")
Reported-by: Nwenxu <wenxu@ucloud.cn>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_offload.c

@@ -336,7 +336,7 @@ static int nft_flow_block_chain(struct nft_base_chain *basechain,
 {
 	struct net_device *dev;
 	struct nft_hook *hook;
-	int err;
+	int err, i = 0;
 
 	list_for_each_entry(hook, &basechain->hook_list, list) {
 		dev = hook->ops.dev;
@@ -344,11 +344,26 @@ static int nft_flow_block_chain(struct nft_base_chain *basechain,
 			continue;
 
 		err = nft_chain_offload_cmd(basechain, dev, cmd);
-		if (err < 0)
+		if (err < 0 && cmd == FLOW_BLOCK_BIND) {
+			if (!this_dev)
+				goto err_flow_block;
+
 			return err;
+		}
+		i++;
 	}
 
 	return 0;
+
+err_flow_block:
+	list_for_each_entry(hook, &basechain->hook_list, list) {
+		if (i-- <= 0)
+			break;
+
+		dev = hook->ops.dev;
+		nft_chain_offload_cmd(basechain, dev, FLOW_BLOCK_UNBIND);
+	}
+	return err;
 }
 
 static int nft_flow_offload_chain(struct nft_chain *chain, u8 *ppolicy,