Q: Given the following code slice:
```
1 static int __uvcg_iter_item_entries(const char *page, size_t len,
2 				    int (*fun)(char *, void *, unsigned int),
3 				    void *priv, unsigned int size)
4 {
5 	/* sign, base 2 representation, newline, terminator */
6 	unsigned int bufsize = 1 + size * 8 + 1 + 1;
7 	const char *pg = page;
8 	int i, ret = 0;
9 	char *buf;
10 
11 	if (!fun)
12 		return -EINVAL;
13 
14 	buf = kzalloc(bufsize, GFP_KERNEL);
15 	if (!buf)
16 		return -ENOMEM;
17 
18 	while (pg - page < len) {
19 		i = 0;
20 		while (i < sizeof(buf) && (pg - page < len) &&
21 		       *pg != '\0' && *pg != '\n')
22 			buf[i++] = *pg++;
23 		if (i == sizeof(buf)) {
24 			ret = -EINVAL;
25 			goto out_free_buf;
26 		}
27 		while ((pg - page < len) && (*pg == '\0' || *pg == '\n'))
28 			++pg;
29 		buf[i] = '\0';
30 		ret = fun(buf, priv, size);
31 		if (ret)
32 			goto out_free_buf;
33 	}
34 
35 out_free_buf:
36 	kfree(buf);
37 	return ret;
38 }
```
which has a vulnerability among CWE-787 and among lines:
```
20 		while (i < sizeof(buf) && (pg - page < len) &&
```
Please generate five possible patches for the vulnerability.