Fix mDNS memory leak

components/mdns/mdns.c

@@ -2296,9 +2296,7 @@ static mdns_service_t * _mdns_create_service(const char * service, const char *
     if (hostname) {
         s->hostname = strndup(hostname, MDNS_NAME_BUF_LEN - 1);
         if (!s->hostname) {
-            free((char *)s->instance);
-            free(s);
-            return NULL;
+            goto fail;
         }
     } else {
         s->hostname = NULL;
@@ -2306,20 +2304,27 @@ static mdns_service_t * _mdns_create_service(const char * service, const char *
 
     s->service = strndup(service, MDNS_NAME_BUF_LEN - 1);
     if (!s->service) {
-        free((char *)s->instance);
-        free(s);
-        return NULL;
+        goto fail;
     }
 
     s->proto = strndup(proto, MDNS_NAME_BUF_LEN - 1);
     if (!s->proto) {
-        free((char *)s->instance);
         free((char *)s->service);
-        free(s);
-        return NULL;
+        goto fail;
     }
 
     return s;
+
+fail:
+    if (s->instance) {
+        free(s->instance);
+    }
+    if (s->hostname) {
+        free(s->hostname);
+    }
+    free(s);
+
+    return NULL;
 }
 
 /**