[Python-Dev] Challenge: Please break this! (a.k.a restricted mode revisited)

[Oleg Broytman]

On Mon, Apr 11, 2016 at 08:06:34AM +0200, Oleg Broytman <phd at phdru.name> wrote:
> On Mon, Apr 11, 2016 at 12:42:47AM -0500, Wes Turner <wes.turner at gmail.com> wrote:
> > On Sun, Apr 10, 2016 at 10:50 PM, Oleg Broytman <phd at phdru.name> wrote:
> > 
> > > On Mon, Apr 11, 2016 at 01:09:19PM +1000, Steven D'Aprano <
> > > steve at pearwood.info> wrote:
> > > > On Sun, Apr 10, 2016 at 08:12:30PM -0400, Jonathan Goble wrote:
> > > > > On Sun, Apr 10, 2016 at 7:02 PM, Oscar Benjamin
> > > > > <oscar.j.benjamin at gmail.com> wrote:
> > > > > > I haven't looked at your sandbox but for a different approach try
> > > this one:
> > > > > >
> > > > > >   L = [None]
> > > > > >   L.extend(iter(L))
> > > > > >
> > > > > > On my Linux machine that doesn't just crash Python.
> > > > >
> > > > > For the record: don't try this if you have unsaved files open on your
> > > > > computer, because you will lose them. When I typed these two lines
> > > > > into the Py3.5 interactive prompt, it completely and totally froze
> > > > > Windows to the point that nothing would respond and I had to resort to
> > > > > the old trick of holding the power button down for five seconds to
> > > > > forcibly shut the computer down.
> > > >
> > > >
> > > > I think this might improve matters:
> > > >
> > > > http://bugs.python.org/issue26351
> > > >
> > > > although I must admit I don't understand why the entire OS is effected.
> > >
> > >    Memory exhaustion?
> > *
> > https://docs.docker.com/compose/compose-file/#cpu-shares-cpu-quota-cpuset-domainname-hostname-ipc-mac-address-mem-limit-memswap-limit-privileged-read-only-restart-stdin-open-tty-user-working-dir
> > 
> > * https://github.com/jupyter/dockerspawner/blob/master/systemuser/Dockerfile
> 
>    I think memory control groups in Linux can be used to limit memory
> usage. I have mem. c. g. configured and I'll try to find time to
> experiment with the code above.

   With limited memory it was fast:

$ ulimit -d 50000 -m 80000 -s 10000 -v 100000
$ python
Python 2.7.9 (default, Mar  1 2015, 18:22:53) 
[GCC 4.9.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> L = [None]
>>> L.extend(iter(L))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
MemoryError

   Memory control groups don't help because they don't limit virtual
memory so the process simply starts thrashing.

> > > > --
> > > > Steve

Oleg.
-- 
     Oleg Broytman            http://phdru.name/            phd at phdru.name
           Programmers don't die, they just GOSUB without RETURN.