Pyvex errors on 32 bit linux

[k0ss]

I was testing angr in a 32 bit kali vm and noticed that no functions were being found by any CFG. During troubleshooting with @ltfish he found that it was a problem with pyvex on my 32 bit version of linux.

(angr) root@kali:~# cat testpyvex.py 
import pyvex
import archinfo
pyvex.IRSB("\xc3", 0, archinfo.arch_from_id('X86')).pp()
(angr) root@kali:~# python testpyvex.py 
Traceback (most recent call last):
  File "testpyvex.py", line 3, in <module>
    pyvex.IRSB("\xc3", 0, archinfo.arch_from_id('X86')).pp()
  File "/root/.virtualenvs/angr/local/lib/python2.7/site-packages/pyvex/block.py", line 60, in __init__
    lift(self, data, num_bytes, num_inst, bytes_offset, traceflags)
  File "/root/.virtualenvs/angr/local/lib/python2.7/site-packages/pyvex/lift/__init__.py", line 88, in lift
    raise PyVEXError('\n\n'.join(errors))
pyvex.errors.PyVEXError: vex: priv/main_main.c:619 (LibVEX_Translate): Assertion `0 == sizeof(VexGuestX86State) % LibVEX_GUEST_STATE_ALIGN' failed

[ltfish]

Confirmed. Assigned to @rhelmot (since he was messing with that part of the code).

[rhelmot]

Resolved via angr/vex@3666b75

This ended up being a really obscure piece of GCC behavior... by default, on 32 bit platforms, gcc will only align 64-bit datatypes to 32 bits. This is some pretty fucked up behavior if you ask me! The flag -malign-double fixes this.

[joeleong]

FYI: I think the patch breaks builds with old versions of clang such as the system version on many versions of OS X. I worked around it by installing a newer version via Homebrew. (More info: https://reviews.llvm.org/D19740)