sctp: pass a kernel pointer to sctp_setsockopt_mappedv4

Use the kernel pointer that sctp_setsockopt has available instead of
directly handling the user pointer.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/socket.c

@@ -3173,16 +3173,14 @@ static int sctp_setsockopt_associnfo(struct sock *sk,
  * addresses and a user will receive both PF_INET6 and PF_INET type
  * addresses on the socket.
  */
-static int sctp_setsockopt_mappedv4(struct sock *sk, char __user *optval, unsigned int optlen)
+static int sctp_setsockopt_mappedv4(struct sock *sk, int *val,
+				    unsigned int optlen)
 {
-	int val;
 	struct sctp_sock *sp = sctp_sk(sk);
 
 	if (optlen < sizeof(int))
 		return -EINVAL;
-	if (get_user(val, (int __user *)optval))
-		return -EFAULT;
-	if (val)
+	if (*val)
 		sp->v4mapped = 1;
 	else
 		sp->v4mapped = 0;
@@ -4696,7 +4694,7 @@ static int sctp_setsockopt(struct sock *sk, int level, int optname,
 		retval = sctp_setsockopt_associnfo(sk, kopt, optlen);
 		break;
 	case SCTP_I_WANT_MAPPED_V4_ADDR:
-		retval = sctp_setsockopt_mappedv4(sk, optval, optlen);
+		retval = sctp_setsockopt_mappedv4(sk, kopt, optlen);
 		break;
 	case SCTP_MAXSEG:
 		retval = sctp_setsockopt_maxseg(sk, optval, optlen);