G “Guard”. Enable guard pages. Each page size or larger allocation is followed by a guard page that will cause a segmentation fault upon any access
How can I enable guard pages to harden an OpenBSD install?
Also, how can I check what is the current status of the malloc settings?
In http://man.openbsd.org/malloc.conf.5 I can see:
Set a systemwide reduction of the cache to a quarter of the default size and use guard pages:
# ln -s 'G<<' /etc/malloc.conf
This probably enabled guard pages, but what is the "<<" and the "reduction of the cache to a quarter of the default size".
I just want to enable guard pages, afaik that is the most secure setting for malloc.conf.