ofz#4570 depth protect mathtype parsing

Change-Id: I1d8ca1704c057e154aa1d3aa57d722c24609cc48
Reviewed-on: https://gerrit.libreoffice.org/46181Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

starmath/source/mathtype.cxx

@@ -646,6 +646,10 @@ void MathType::HandleNudge()
 bool MathType::HandleRecords(int nLevel, sal_uInt8 nSelector,
     sal_uInt8 nVariation, int nMatrixRows, int nMatrixCols)
 {
+    //depth-protect
+    if (nLevel > 2048)
+        return false;
+
     sal_uInt8 nTag,nRecord;
     sal_uInt8 nTabType,nTabStops;
     sal_uInt16 nTabOffset;