Q: Given the following code slice:
```
1 static int remove_device_files(struct super_block *sb,
2 			       struct qib_devdata *dd)
3 {
4 	struct dentry *dir;
5 	char unit[10];
6 
7 	snprintf(unit, sizeof(unit), "%u", dd->unit);
8 	dir = lookup_one_len_unlocked(unit, sb->s_root, strlen(unit));
9 
10 	if (IS_ERR(dir)) {
11 		pr_err("Lookup of %s failed\n", unit);
12 		return PTR_ERR(dir);
13 	}
14 	simple_recursive_removal(dir, NULL);
15 	return 0;
16 }
```
which has a vulnerability among CWE-476 and among lines:
```
14 	simple_recursive_removal(dir, NULL);
```
Please generate five possible patches for the vulnerability.