Comment 18 for bug 807893

Actually, from a quick google perhaps ensuring all threads run after chroot / dropping privileges might be a good idea.

- http://wiki.freebsd.org/Per-Thread%20Credentials
- http://www.cocoabuilder.com/archive/cocoa/33107-cthread-fork.html

though it looks like you might need to put in effort into getting per-thread uid's for freebsd/macosx when they make that available, and you're assuming they're running a recent glibc. Depending on complexity, it can't hurt to ensure you're not going to hit into per-thread uid/gid's. I'm of two minds about glibc doing this. This was a particular favourite bug class of mine :)

It seems that there is a linux distro which uses uclibc, which does not emulate the glibc behaviour:

http://dl-4.alpinelinux.org/alpine/v2.2/main/x86/ <-- has qemu packages.

we can use http://paste.pocoo.org/raw/438497/ to emulate qemu's behaviour

# ./test
[main] my [ug]id is 100/100
[thread] my [ug]id is 0/0

^-- the qemu thread would be running as root

running the same code under glibc (without grsecurity chroot_findtask), and it will drop privileges as you'd expect on recent glibc.