[systemd-devel] /run DoS

[Lennart Poettering]

On Sun, 03.04.11 15:55, Michał Piotrowski (mkkp4x4 at gmail.com) wrote:

> 
> W dniu 3 kwietnia 2011 12:54 użytkownik Lennart Poettering
> <mzerqung at 0pointer.de> napisał:
> > On Sun, 03.04.11 13:10, Michał Piotrowski (mkkp4x4 at gmail.com) wrote:
> >
> >> Hi,
> >>
> >> I can write to /run/user/michal in this way I can fill the entire free
> >> tmpfs space which is not good from my POV.
> >
> > Yupp, this is trivially fixable by placing another tmpfs on /run/user,
> > which can be done by installing a run-user.mount unit.
> >
> > We considered doing so by default, but stepped back a little, since we
> > didn't want to add another tmpfs to the mix, just like that. But yeah,
> > we probably should do that.
> 
> I see no other way out here because tmpfs does not support quota.
> 
> BTW. There still be a possibility to deadlock machine if you have a
> not limited /tmp on tmpfs. By default tmpfs can use a half of system
> memory size, so if you got a two user writable tmpfs file systems you
> can try to deadlock system.

Well, you can trigger an OOM situation with this. It's much easier to do
with malloc() and by touching some memory.

Lennart

-- 
Lennart Poettering - Red Hat, Inc.