add test

Author: devnexen

ext/gd/tests/gh17772.phpt

@@ -0,0 +1,24 @@
+--TEST--
+GH-17772 (imagepalettetotruecolor segfault on image deallocation)
+--EXTENSIONS--
+gd
+--INI--
+memory_limit=2M
+--CREDITS--
+YuanchengJiang
+--FILE--
+<?php
+function setStyleAndThickness($im, $color, $thickness)
+{
+$arr = [];
+$i = 0;
+while ($i < 16 * $thickness) {
+$arer[$i++] = $color;
+}
+}
+$im = imagecreate(800, 800);
+setStyleAndThickness($im, 0, 6);
+imagepalettetotruecolor($im);
+?>
+--EXPECTF--
+Fatal error: Allowed memory size of %d bytes exhausted%s(tried to allocate %d bytes) in %s on line %d