staging: gdm72xx: add userspace data struct

This fixes the sparse warnings about dereferencing a userspace pointer.

Once I updated the sparse annotations, I noticed a bug in
gdm_wimax_ioctl() where we pass a user space pointer to gdm_update_fsm()
which dereferences it. I fixed this.

Signed-off-by: Wim de With <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/gdm72xx/gdm_wimax.c

···
 	}
 }
 
-static int gdm_wimax_ioctl_get_data(struct data_s *dst, struct data_s *src)
+static int gdm_wimax_ioctl_get_data(struct udata_s *dst, struct data_s *src)
 {
 	int size;
 
···
 	return 0;
 }
 
-static int gdm_wimax_ioctl_set_data(struct data_s *dst, struct data_s *src)
+static int gdm_wimax_ioctl_set_data(struct data_s *dst, struct udata_s *src)
 {
 	if (!src->size) {
 		dst->size = 0;
···
 	struct wm_req_s *req = (struct wm_req_s *)ifr;
 	struct nic *nic = netdev_priv(dev);
 	int ret;
+	struct fsm_s fsm_buf;
 
 	if (cmd != SIOCWMIOCTL)
 		return -EOPNOTSUPP;
···
 				/* NOTE: gdm_update_fsm should be called
 				 * before gdm_wimax_ioctl_set_data is called.
 				 */
-				gdm_update_fsm(dev,
-					       req->data.buf);
+				if (copy_from_user(&fsm_buf, req->data.buf,
+						   sizeof(struct fsm_s)))
+					return -EFAULT;
+
+				gdm_update_fsm(dev, &fsm_buf);
 			}
 			ret = gdm_wimax_ioctl_set_data(
 				&nic->sdk_data[req->data_id], &req->data);

drivers/staging/gdm72xx/wm_ioctl.h

···
 	void	*buf;
 };
 
+struct udata_s {
+	int		size;
+	void __user	*buf;
+};
+
 struct wm_req_s {
 	union {
 		char ifrn_name[IFNAMSIZ];
 	} ifr_ifrn;
 	unsigned short	cmd;
 	unsigned short	data_id;
-	struct data_s	data;
+	struct udata_s	data;
 
 /* NOTE: sizeof(struct wm_req_s) must be less than sizeof(struct ifreq). */
 };