It crashed when you tried to edit a master page. Is the crash reproducible?

No luck here. a11y does not have any effect either.

Nothing with repeated attempts. ToDo: retry under valgrind

Nothing reported under valgrind. Works for me fine, and there's no indication in the bt that GetSelectedMasterPage returns NULL there but it must have returned something bogus to crash there. All very mysterious.

GetSelectedMasterPage can in theory return NULL, so fixed that code to be stable in the face of that happening on the off chance that optimization has led gdb to report that variable as a non-NULL value which actually being NULL.

libreoffice-3.6.5.2-6.fc18 has been submitted as an update for Fedora 18.
https://admin.fedoraproject.org/updates/libreoffice-3.6.5.2-6.fc18

Package libreoffice-3.6.5.2-6.fc18:
* should fix your issue,
* was pushed to the Fedora 18 testing repository,
* should be available at your local mirror within two days.
Update it with:
# su -c 'yum update --enablerepo=updates-testing libreoffice-3.6.5.2-6.fc18'
as soon as you are able to.
Please go to the following url:
https://admin.fedoraproject.org/updates/FEDORA-2013-3597/libreoffice-3.6.5.2-6.fc18
then log in and leave karma (feedback).

libreoffice-3.6.5.2-6.fc18 has been pushed to the Fedora 18 stable repository.  If problems still persist, please make note of it in this bug report.