nrf9160 secure services causing a crash

I have been trying to use the secure services to read random from the CC310 and have been getting unpredictable crashes. I have been able to modify the secure_services sample code to create a crash, but it's the oddest thing. The combination of CONFIG_LOG=y and CONFIG_DK_LIBRARY=y along with a call to dk_buttons_init() is enough to cause the exception. No buttons need to be pressed and no log messages generated by me.

I'm using ncs 1.2.0 on a nRF9160 DK. Can anybody explain what's happening? Modified secure_services sample attached