static long do_tee(struct file *in, struct file *out, size_t len,
		   unsigned int flags)
{
	struct pipe_inode_info *ipipe = get_pipe_info(in);
	struct pipe_inode_info *opipe = get_pipe_info(out);
	int ret = -EINVAL;

	/*
	 * Duplicate the contents of ipipe to opipe without actually
	 * copying the data.
	 */
	if (ipipe && opipe && ipipe != opipe) {
		/*
		 * Keep going, unless we encounter an error. The ipipe/opipe
		 * ordering doesn't really matter.
		 */
		ret = ipipe_prep(ipipe, flags);
		if (!ret) {
			ret = opipe_prep(opipe, flags);
			if (!ret)
				ret = link_pipe(ipipe, opipe, len, flags);
		}
	}

	return ret;
}

This category addresses vulnerabilities caused by flawed access control mechanisms, where incorrect permission settings allow unauthorized users to access restricted resources.