NFS: Verify IPv6 addresses properly

Add support to nfs_verify_server_address for recognizing AF_INET6
addresses.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/super.c

@@ -600,16 +600,21 @@ static void nfs_umount_begin(struct vfsmount *vfsmnt, int flags)
 }
 
 /*
- * Sanity-check a server address provided by the mount command
+ * Sanity-check a server address provided by the mount command.
+ *
+ * Address family must be initialized, and address must not be
+ * the ANY address for that family.
  */
 static int nfs_verify_server_address(struct sockaddr *addr)
 {
 	switch (addr->sa_family) {
 	case AF_INET: {
-		struct sockaddr_in *sa = (struct sockaddr_in *) addr;
-		if (sa->sin_addr.s_addr != INADDR_ANY)
-			return 1;
-		break;
+		struct sockaddr_in *sa = (struct sockaddr_in *)addr;
+		return sa->sin_addr.s_addr != INADDR_ANY;
+	}
+	case AF_INET6: {
+		struct in6_addr *sa = &((struct sockaddr_in6 *)addr)->sin6_addr;
+		return !ipv6_addr_any(sa);
 	}
 	}