The ProcPutImage function in dix/dispatch.c in X.Org Server (aka xserver and xorg-server) before 1.16.4 allows attackers to cause a denial of service (divide-by-zero and crash) via a zero-height PutImage request.
https://security.gentoo.org/glsa/201701-64
https://lists.x.org/archives/xorg-announce/2015-February/002532.html
https://cgit.freedesktop.org/xorg/xserver/commit/?id=dc777c346d5d452a53b13b917c45f6a1bad2f20b
http://www.securityfocus.com/bid/74328
http://www.oracle.com/technetwork/topics/security/bulletinapr2015-2511959.html