Q: Given the following code slice:
```
1 static int nfc_llcp_setsockopt(struct socket *sock, int level, int optname,
2 			       sockptr_t optval, unsigned int optlen)
4 	struct sock *sk = sock->sk;
6 	u32 opt;
11 	if (level != SOL_NFC)
16 	switch (optname) {
18 		if (sk->sk_state == LLCP_CONNECTED ||
25 		if (copy_from_sockptr(&opt, optval, sizeof(u32))) {```
which has a CWE-787 vulnerability at line:
```
25 		if (copy_from_sockptr(&opt, optval, sizeof(u32))) {
```
Please analyze the root cause of the vulnerability.