Arguments::add_property function in src/share/vm/runtime/arguments.cpp is used to add property.
This function allocated memory for key and value(in case if value is passed):

bool Arguments::add_property(const char* prop) {
...
  key = AllocateHeap(key_len + 1, mtInternal);
  strncpy(key, prop, key_len);
  key[key_len] = '\0';


  if (eq != NULL) {
    size_t value_len = strlen(prop) - key_len - 1;
    value = AllocateHeap(value_len + 1, mtInternal);
    strncpy(value, &prop[key_len + 1], value_len + 1);
  }


The property is updated by calling PropertyList_unique_add and passing 'key' and 'value' to this function:
bool Arguments::add_property(const char* prop) {
...
    _java_vendor_url_bug = value;
  } else if (strcmp(key, "sun.boot.library.path") == 0) {
    PropertyList_unique_add(&_system_properties, key, value, true);
    return true;
  }

  // Create new property and add at the end of the list
  PropertyList_unique_add(&_system_properties, key, value);
  return true;
}


PropertyList_unique_add function look for existing property and update(or append to) value of property, or create a new property.
void Arguments::PropertyList_unique_add(SystemProperty** plist, const char* k, char* v, jboolean append) {
  if (plist == NULL)
    return;

  // If property key exist then update with new value.
  SystemProperty* prop;
  for (prop = *plist; prop != NULL; prop = prop->next()) {
    if (strcmp(k, prop->key()) == 0) {
      if (append) {
        prop->append_value(v);
      } else {
        prop->set_value(v);
      }
      return;
    }
  }

  PropertyList_add(plist, k, v);
}

The problem is following: SystemProperty contains it's own copy of the key and value and always copy provided data to it(when creating SystemProperty or when updating it via append_value or set_value). Therefore Arguments::add_property should free 'key' and 'value' after calling to PropertyList_unique_add function.

Also, Arguments::add_property not check return value of AllocateHeap function when allocating 'key' and 'value'.