void fsck_set_msg_types(struct fsck_options *options, const char *values)
{
	char *buf = xstrdup(values), *to_free = buf;
	int done = 0;

	while (!done) {
		int len = strcspn(buf, " ,|"), equal;

		done = !buf[len];
		if (!len) {
			buf++;
			continue;
		}
		buf[len] = '\0';

		for (equal = 0;
		     equal < len && buf[equal] != '=' && buf[equal] != ':';
		     equal++)
			buf[equal] = tolower(buf[equal]);
		buf[equal] = '\0';

		if (!strcmp(buf, "skiplist")) {
			if (equal == len)
				die("skiplist requires a path");
			init_skiplist(options, buf + equal + 1);
			buf += len + 1;
			continue;
		}

		if (equal == len)
			die("Missing '=': '%s'", buf);

		fsck_set_msg_type(options, buf, buf + equal + 1);
		buf += len + 1;
	}
	free(to_free);
}

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.