Booting kernel-4.5.0-0.rc2.git3.2.fc24.x86_64 with secure boot enabled gives: double free at 0x6c9be280 Aborted. press aby key to exit. Booting with secure boot disabled works fine.
I'm pretty sure the kernel is signed correctly and the double free is from grub itself. This should probably be punted over the grub as I don't think there's anything we can do in the kernel here.
This is a pretty old issue that should be fixed now.