tty/vt: consolemap: check put_user() in con_get_unimap()

Only the return value of copy_to_user() is checked in con_get_unimap().
Do the same for put_user() of the count too.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220607104946.18710-16-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/vt/consolemap.c

@@ -813,7 +813,8 @@ int con_get_unimap(struct vc_data *vc, ushort ct, ushort __user *uct,
 	console_unlock();
 	if (copy_to_user(list, unilist, min(ect, ct) * sizeof(*unilist)))
 		ret = -EFAULT;
-	put_user(ect, uct);
+	if (put_user(ect, uct))
+		ret = -EFAULT;
 	kvfree(unilist);
 	return ret ? ret : (ect <= ct) ? 0 : -ENOMEM;
 }