X.org Render extension input validation flaw causing memory corruption

Multiple integer overflows in the Render extension in the X server 1.4 in X.Org X11R7.3 allow context-dependent attackers to execute arbitrary code via a 1 SProcRenderCreateLinearGradient, 2 SProcRenderCreateRadialGradient, or 3 SProcRenderCreateConicalGradient request with an invalid field...