static int megasas_mgmt_fasync(int fd, struct file *filep, int mode)
{
	int rc;

	mutex_lock(&megasas_async_queue_mutex);

	rc = fasync_helper(fd, filep, mode, &megasas_async_queue);

	mutex_unlock(&megasas_async_queue_mutex);

	if (rc >= 0) {
		/* For sanity check when we get ioctl */
		filep->private_data = filep;
		return 0;
	}

	printk(KERN_DEBUG "megasas: fasync_helper failed [%d]\n", rc);

	return rc;
}

The product dereferences a pointer that it expects to be valid but is NULL.