ofz: loop detect

Change-Id: Ie0b54686e1406c5114148f9fe9a0bacfb5b607e8
Reviewed-on: https://gerrit.libreoffice.org/48899Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

lotuswordpro/source/filter/lwpdoc.cxx

@@ -312,11 +312,15 @@ void LwpDocument::RegisterBulletStyles()
         return;
     LwpSilverBullet* pBullet = dynamic_cast<LwpSilverBullet*>
                         (pBulletHead->GetHeadID().obj().get());
-    while(pBullet)
+    std::set<LwpSilverBullet*> aSeen;
+    while (pBullet)
     {
+        aSeen.insert(pBullet);
         pBullet->SetFoundry(m_pFoundry);
         pBullet->RegisterStyle();
         pBullet = dynamic_cast<LwpSilverBullet*> (pBullet->GetNext().obj().get());
+        if (aSeen.find(pBullet) != aSeen.end())
+            throw std::runtime_error("loop in conversion");
     }
 }
 /**