netfilter: nft_tunnel: add the missing nla_nest_cancel()

When nla_put_xxx() fails under nla_nest_start_noflag(),
nla_nest_cancel() should be called, so that the skb can
be trimmed properly.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_tunnel.c

@@ -443,10 +443,15 @@ static int nft_tunnel_ip_dump(struct sk_buff *skb, struct ip_tunnel_info *info)
 		if (!nest)
 			return -1;
 
-		if (nla_put_in6_addr(skb, NFTA_TUNNEL_KEY_IP6_SRC, &info->key.u.ipv6.src) < 0 ||
-		    nla_put_in6_addr(skb, NFTA_TUNNEL_KEY_IP6_DST, &info->key.u.ipv6.dst) < 0 ||
-		    nla_put_be32(skb, NFTA_TUNNEL_KEY_IP6_FLOWLABEL, info->key.label))
+		if (nla_put_in6_addr(skb, NFTA_TUNNEL_KEY_IP6_SRC,
+				     &info->key.u.ipv6.src) < 0 ||
+		    nla_put_in6_addr(skb, NFTA_TUNNEL_KEY_IP6_DST,
+				     &info->key.u.ipv6.dst) < 0 ||
+		    nla_put_be32(skb, NFTA_TUNNEL_KEY_IP6_FLOWLABEL,
+				 info->key.label)) {
+			nla_nest_cancel(skb, nest);
 			return -1;
+		}
 
 		nla_nest_end(skb, nest);
 	} else {
@@ -454,9 +459,13 @@ static int nft_tunnel_ip_dump(struct sk_buff *skb, struct ip_tunnel_info *info)
 		if (!nest)
 			return -1;
 
-		if (nla_put_in_addr(skb, NFTA_TUNNEL_KEY_IP_SRC, info->key.u.ipv4.src) < 0 ||
-		    nla_put_in_addr(skb, NFTA_TUNNEL_KEY_IP_DST, info->key.u.ipv4.dst) < 0)
+		if (nla_put_in_addr(skb, NFTA_TUNNEL_KEY_IP_SRC,
+				    info->key.u.ipv4.src) < 0 ||
+		    nla_put_in_addr(skb, NFTA_TUNNEL_KEY_IP_DST,
+				    info->key.u.ipv4.dst) < 0) {
+			nla_nest_cancel(skb, nest);
 			return -1;
+		}
 
 		nla_nest_end(skb, nest);
 	}
@@ -477,37 +486,42 @@ static int nft_tunnel_opts_dump(struct sk_buff *skb,
 	if (opts->flags & TUNNEL_VXLAN_OPT) {
 		inner = nla_nest_start_noflag(skb, NFTA_TUNNEL_KEY_OPTS_VXLAN);
 		if (!inner)
-			return -1;
+			goto failure;
 		if (nla_put_be32(skb, NFTA_TUNNEL_KEY_VXLAN_GBP,
 				 htonl(opts->u.vxlan.gbp)))
-			return -1;
+			goto inner_failure;
 		nla_nest_end(skb, inner);
 	} else if (opts->flags & TUNNEL_ERSPAN_OPT) {
 		inner = nla_nest_start_noflag(skb, NFTA_TUNNEL_KEY_OPTS_ERSPAN);
 		if (!inner)
-			return -1;
+			goto failure;
 		if (nla_put_be32(skb, NFTA_TUNNEL_KEY_ERSPAN_VERSION,
 				 htonl(opts->u.erspan.version)))
-			return -1;
+			goto inner_failure;
 		switch (opts->u.erspan.version) {
 		case ERSPAN_VERSION:
 			if (nla_put_be32(skb, NFTA_TUNNEL_KEY_ERSPAN_V1_INDEX,
 					 opts->u.erspan.u.index))
-				return -1;
+				goto inner_failure;
 			break;
 		case ERSPAN_VERSION2:
 			if (nla_put_u8(skb, NFTA_TUNNEL_KEY_ERSPAN_V2_HWID,
 				       get_hwid(&opts->u.erspan.u.md2)) ||
 			    nla_put_u8(skb, NFTA_TUNNEL_KEY_ERSPAN_V2_DIR,
 				       opts->u.erspan.u.md2.dir))
-				return -1;
+				goto inner_failure;
 			break;
 		}
 		nla_nest_end(skb, inner);
 	}
 	nla_nest_end(skb, nest);
-
 	return 0;
+
+inner_failure:
+	nla_nest_cancel(skb, inner);
+failure:
+	nla_nest_cancel(skb, nest);
+	return -1;
 }
 
 static int nft_tunnel_ports_dump(struct sk_buff *skb,