SafeStack in base

Hey All,

I'm interested in getting SafeStack working in FreeBSD base. Below is a
link to a simplistic (maybe too simplistic?) patch to enable SafeStack.
The patch applies against HardenedBSD's hardened/current/master branch.
Given how simple the patch is, it'd be extremely easy to port over to
FreeBSD (just line numbers would change).

I am running into a bit of a problem, though. When linking
lib/libcom_err, I get the following error:

com_err.So: In function `com_err':
/usr/src/lib/libcom_err/../../contrib/com_err/com_err.c:100: undefined reference to `__safestack_unsafe_stack_ptr'
cc: error: linker command failed with exit code 1 (use -v to see invocation)
*** [libcom_err.so.5.full] Error code 1

llvm's documentation says that SafeStack has been tested on FreeBSD.
When and how was it tested? Apparently someone has done some work to
enable it on FreeBSD, but I can't find any relevant FreeBSD-specific
documentation.

If someone could point me in the right direction, I'd love to help get
SafeStack working (and commited?) in FreeBSD.

Link to simplistic patch: http://ix.io/186A
Link to build log: https://gist.github.com/lattera/5d94f44a5f3e10a28425cd59104dd169

Thanks,

-- 
Shawn Webb
Cofounder and Security Engineer
HardenedBSD

GPG Key ID:          0x6A84658F52456EEE
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