[pypy-dev] W^X in the PyPy JIT?

[Edd Barrett]

Hi!

Recently OpenBSD has started enforcing W^X [1] for all programs, unless
the program is on a file system with a special 'wxallowed' flag.

Regardless of the flag, a message is emitted to the dmesg buffer.
Starting PyPy will emit such a message:

pypy(62301): mmap W^X violation

I suppose the memory the JIT is using for traces has been mapped W+X?
Assuming this is the case, the security of PyPy (on all platforms) could
be improved by mapping the memory W during trace compilation, and then
re-mapping the memory X once compilation is complete.

Of course, it might not be the JIT at all...

Cheers

[1] https://en.wikipedia.org/wiki/W%5EX

-- 
Best Regards
Edd Barrett

http://www.theunixzoo.co.uk