Solved Hang after disabling kern.elf64.nxstack

[loveydovey]

Major hang happens if I set kern.elf64.nxstack=0. I normally have it =1, so if I try to manually disable it by setting it to 0, everything breaks and I get an error trying to do anything:

[user@freebsd ~]$ sudo sysctl kern.elf64.nxstack=0
kern.elf64.nxstack: 1 -> 0
[user@freebsd ~]$ sudo sysctl kern.elf32.nxstack=0
exec_new_vmspace: mapping stack size 0x20000000 prot 0x7 failed, mach error 2 errno 13
Abort trap                 sudo sysctl kern.elf32.nxstack=0
[user@freebsd ~]$ sudo sysctl kern.elf32.nxstack
exec_new_vmspace: mapping stack size 0x20000000 prot 0x7 failed, mach error 2 errno 13
Abort trap                 sudo sysctl kern.elf32.nxstack

If I set it to 0 in /etc/sysctl.conf, I can't even boot into the system, similar error message, unknown error 134, says "init crashes", and I'm stuck in a login loop for single-user mode.

 

[loveydovey]

Ok, this is expected behavior. Thanks!

 

[SirDice]

You typically do not want this turned off. It prevents the baddies from being able to inject executable code in data. Though they can still inject it, just not pass execution to it (thwarts a certain category of exploits).

If you really want this off, do so in your BIOS/UEFI.