Given the following code containing errors, provide Common Weakness Enumeration (CWE) identifiers and corresponding messages in JSON format. Each identified weakness should have a unique entry in the JSON array.
    Code: static int __must_check ax25_rt_add(struct ax25_routes_struct *route)
{
	ax25_route *ax25_rt;
	ax25_dev *ax25_dev;
	int i;

	if ((ax25_dev = ax25_addr_ax25dev(&route->port_addr)) == NULL)
		return -EINVAL;
	if (route->digi_count > AX25_MAX_DIGIS)
		return -EINVAL;

	write_lock_bh(&ax25_route_lock);

	ax25_rt = ax25_route_list;
	while (ax25_rt != NULL) {
		if (ax25cmp(&ax25_rt->callsign, &route->dest_addr) == 0 &&
			    ax25_rt->dev == ax25_dev->dev) {
			kfree(ax25_rt->digipeat);
			ax25_rt->digipeat = NULL;
			if (route->digi_count != 0) {
				if ((ax25_rt->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
					write_unlock_bh(&ax25_route_lock);
					return -ENOMEM;
				}
				ax25_rt->digipeat->lastrepeat = -1;
				ax25_rt->digipeat->ndigi      = route->digi_count;
				for (i = 0; i < route->digi_count; i++) {
					ax25_rt->digipeat->repeated[i] = 0;
					ax25_rt->digipeat->calls[i]    = route->digi_addr[i];
				}
			}
			write_unlock_bh(&ax25_route_lock);
			return 0;
		}
		ax25_rt = ax25_rt->next;
	}

	if ((ax25_rt = kmalloc(sizeof(ax25_route), GFP_ATOMIC)) == NULL) {
		write_unlock_bh(&ax25_route_lock);
		return -ENOMEM;
	}

	refcount_set(&ax25_rt->refcount, 1);
	ax25_rt->callsign     = route->dest_addr;
	ax25_rt->dev          = ax25_dev->dev;
	ax25_rt->digipeat     = NULL;
	ax25_rt->ip_mode      = ' ';
	if (route->digi_count != 0) {
		if ((ax25_rt->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
			write_unlock_bh(&ax25_route_lock);
			kfree(ax25_rt);
			return -ENOMEM;
		}
		ax25_rt->digipeat->lastrepeat = -1;
		ax25_rt->digipeat->ndigi      = route->digi_count;
		for (i = 0; i < route->digi_count; i++) {
			ax25_rt->digipeat->repeated[i] = 0;
			ax25_rt->digipeat->calls[i]    = route->digi_addr[i];
		}
	}
	ax25_rt->next   = ax25_route_list;
	ax25_route_list = ax25_rt;
	write_unlock_bh(&ax25_route_lock);

	return 0;
} ; Sample JSON Format Confermily Expected output: "examples" => "cwe": "xxx"; "message": "xxx"
    
 'cwe': ['CWE-416'], 'message': 'ax25: add refcount in ax25_dev to avoid UAF bugs

If we dereference ax25_dev after we call kfree(ax25_dev) in
ax25_dev_device_down(), it will lead to concurrency UAF bugs.
There are eight syscall functions suffer from UAF bugs, include
ax25_bind(), ax25_release(), ax25_connect(), ax25_ioctl(),
ax25_getname(), ax25_sendmsg(), ax25_getsockopt() and
ax25_info_show().

One of the concurrency UAF can be shown as below:

  (USE)                       |    (FREE)
                              |  ax25_device_event
                              |    ax25_dev_device_down
ax25_bind                     |    ...
  ...                         |      kfree(ax25_dev)
  ax25_fillin_cb()            |    ...
    ax25_fillin_cb_from_dev() |
  ...                         |

The root cause of UAF bugs is that kfree(ax25_dev) in
ax25_dev_device_down() is not protected by any locks.
When ax25_dev, which there are still pointers point to,
is released, the concurrency UAF bug will happen.

This patch introduces refcount into ax25_dev in order to
guarantee that there are no pointers point to it when ax25_dev
is released.

Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>'