Backported from X.org:

  From 446ff2d3177087b8173fa779fa5b77a2a128988b Mon Sep 17 00:00:00 2001
  From: Matthieu Herrb <matthieu@herrb.eu>
  Date: Thu, 12 Nov 2020 19:15:07 +0100
  Subject: [PATCH] Check SetMap request length carefully.

  Avoid out of bounds memory accesses on too short request.

  ZDI-CAN 11572 /  CVE-2020-14360

  This vulnerability was discovered by:
  Jan-Niklas Sohn working with Trend Micro Zero Day Initiative

  Fixes ArcticaProject/nx-libs#972.