+static int copy_msghdr_from_user(struct msghdr *kmsg,
+ struct msghdr __user *umsg)
+{
+ if (copy_from_user(kmsg, umsg, sizeof(struct msghdr)))
+ return -EFAULT;
+
+ if (kmsg->msg_name == NULL)
+ kmsg->msg_namelen = 0;
+
+ if (kmsg->msg_namelen < 0)
+ return -EINVAL;
+
+ if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
+ kmsg->msg_namelen = sizeof(struct sockaddr_storage);
+ return 0;
+}
+