It was possible to end up with a dangling pointer in m_listStack, which could result in use-after-free.
Upstream Reference: https://codereview.qt-project.org/c/qt/qtbase/+/291706
Created qt tracking bugs for this issue: Affects: fedora-all [bug 1837480] Created qt3 tracking bugs for this issue: Affects: fedora-all [bug 1837482]
Created qt5 tracking bugs for this issue: Affects: fedora-all [bug 1837484]