static long ec_device_ioctl_readmem(struct cros_ec_dev *ec, void __user *arg)
{
	struct cros_ec_device *ec_dev = ec->ec_dev;
	struct cros_ec_readmem s_mem = { };
	long num;

	/* Not every platform supports direct reads */
	if (!ec_dev->cmd_readmem)
		return -ENOTTY;

	if (copy_from_user(&s_mem, arg, sizeof(s_mem)))
		return -EFAULT;

	num = ec_dev->cmd_readmem(ec_dev, s_mem.offset, s_mem.bytes,
				  s_mem.buffer);
	if (num <= 0)
		return num;

	if (copy_to_user((void __user *)arg, &s_mem, sizeof(s_mem)))
		return -EFAULT;

	return 0;
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.