Q: Given the following code slice:
```
1 static int __key_instantiate_and_link(struct key *key,
2 				      struct key_preparsed_payload *prep,
3 				      struct key *keyring,
4 				      struct key *authkey,
5 				      struct assoc_array_edit **_edit)
6 {
7 	int ret, awaken;
8 
9 	key_check(key);
10 	key_check(keyring);
11 
12 	awaken = 0;
13 	ret = -EBUSY;
14 
15 	mutex_lock(&key_construction_mutex);
16 
17 	/* can't instantiate twice */
18 	if (key->state == KEY_IS_UNINSTANTIATED) {
19 		/* instantiate the key */
20 		ret = key->type->instantiate(key, prep);
21 
22 		if (ret == 0) {
23 			/* mark the key as being instantiated */
24 			atomic_inc(&key->user->nikeys);
25 			mark_key_instantiated(key, 0);
26 			notify_key(key, NOTIFY_KEY_INSTANTIATED, 0);
27 
28 			if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
29 				awaken = 1;
30 
31 			/* and link it into the destination keyring */
32 			if (keyring) {
33 				if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
34 					set_bit(KEY_FLAG_KEEP, &key->flags);
35 
36 				__key_link(keyring, key, _edit);
37 			}
38 
39 			/* disable the authorisation key */
40 			if (authkey)
41 				key_invalidate(authkey);
42 
43 			key_set_expiry(key, prep->expiry);
44 		}
45 	}
46 
47 	mutex_unlock(&key_construction_mutex);
48 
49 	/* wake up anyone waiting for a key to be constructed */
50 	if (awaken)
51 		wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
52 
53 	return ret;
54 }
```
which has a vulnerability among CWE-190 and among lines:
```
43 			key_set_expiry(key, prep->expiry);
```
Please generate five possible patches for the vulnerability.