static ssize_t sock_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
	struct file *file = iocb->ki_filp;
	struct socket *sock = file->private_data;
	struct msghdr msg = {.msg_iter = *to,
			     .msg_iocb = iocb};
	ssize_t res;

	if (file->f_flags & O_NONBLOCK)
		msg.msg_flags = MSG_DONTWAIT;

	if (iocb->ki_pos != 0)
		return -ESPIPE;

	if (!iov_iter_count(to))	/* Match SYS5 behaviour */
		return 0;

	res = sock_recvmsg(sock, &msg, iov_iter_count(to), msg.msg_flags);
	*to = msg.msg_iter;
	return res;
}

Historically, this outdated classification described vulnerabilities from improper handling of data inputs, leading to unexpected program behavior or errors when input validation fails.