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: int key_reject_and_link(struct key *key,
			unsigned timeout,
			unsigned error,
			struct key *keyring,
			struct key *authkey)
{
	struct assoc_array_edit *edit;
	struct timespec now;
	int ret, awaken, link_ret = 0;

	key_check(key);
	key_check(keyring);

	awaken = 0;
	ret = -EBUSY;

	if (keyring) {
		if (keyring->restrict_link)
			return -EPERM;

		link_ret = __key_link_begin(keyring, &key->index_key, &edit);
	}

	mutex_lock(&key_construction_mutex);

	/* can't instantiate twice */
	if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
		/* mark the key as being negatively instantiated */
		atomic_inc(&key->user->nikeys);
		key->reject_error = -error;
		smp_wmb();
		set_bit(KEY_FLAG_NEGATIVE, &key->flags);
		set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
		now = current_kernel_time();
		key->expiry = now.tv_sec + timeout;
		key_schedule_gc(key->expiry + key_gc_delay);

		if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
			awaken = 1;

		ret = 0;

		/* and link it into the destination keyring */
		if (keyring && link_ret == 0)
			__key_link(key, &edit);

		/* disable the authorisation key */
		if (authkey)
			key_revoke(authkey);
	}

	mutex_unlock(&key_construction_mutex);

	if (keyring && link_ret == 0)
		__key_link_end(keyring, &key->index_key, edit);

	/* wake up anyone waiting for a key to be constructed */
	if (awaken)
		wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);

	return ret == 0 ? link_ret : ret;
} ; Sample JSON Format Confermily Expected output: "examples" => "cwe": "xxx"; "message": "xxx"
    
 'cwe': ['CWE-20'], 'message': 'KEYS: Fix race between updating and finding a negative key

Consolidate KEY_FLAG_INSTANTIATED, KEY_FLAG_NEGATIVE and the rejection
error into one field such that:

 (1) The instantiation state can be modified/read atomically.

 (2) The error can be accessed atomically with the state.

 (3) The error isn't stored unioned with the payload pointers.

This deals with the problem that the state is spread over three different
objects (two bits and a separate variable) and reading or updating them
atomically isn't practical, given that not only can uninstantiated keys
change into instantiated or rejected keys, but rejected keys can also turn
into instantiated keys - and someone accessing the key might not be using
any locking.

The main side effect of this problem is that what was held in the payload
may change, depending on the state.  For instance, you might observe the
key to be in the rejected state.  You then read the cached error, but if
the key semaphore wasn't locked, the key might've become instantiated
between the two reads - and you might now have something in hand that isn't
actually an error code.

The state is now KEY_IS_UNINSTANTIATED, KEY_IS_POSITIVE or a negative error
code if the key is negatively instantiated.  The key_is_instantiated()
function is replaced with key_is_positive() to avoid confusion as negative
keys are also 'instantiated'.

Additionally, barriering is included:

 (1) Order payload-set before state-set during instantiation.

 (2) Order state-read before payload-read when using the key.

Further separate barriering is necessary if RCU is being used to access the
payload content after reading the payload pointers.

Fixes: 146aa8b1453b ("KEYS: Merge the type-specific data with the payload data")
Cc: stable@vger.kernel.org # v4.4+
Reported-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>'