[Mageia-dev] forkbomb protection

[David W. Hodgins]

On Wed, 28 Nov 2012 13:00:05 -0500, Johnny A. Solbu <cooker at solbu.net> wrote:

> On Wednesday 28. November 2012 17.53, David Walser wrote:
>> Their pam package has a /etc/security/limits.d/90-nproc.conf file that has:
>
>> *        soft    nproc    1024
>>
>> As the last comment on the bug says, it's a bit confusing that it's in limits.d/ and not the limits.conf file itself,
>
> His point is that any limits set in «/etc/security/limits.d/» overrides the «limits.conf» file.
>
>> and in fact I'm not sure what is responsible for processing limits.d/* as limits.conf says nothing about it (Fedora's is the exact same as ours).
>
> We should add some comments in «/etc/security/limits.conf» about it.
>
>> Anyway, one way or another it would be nice to have this limit set by default on Mageia, IMHO.  WDYT?
>
> I think we should have this.

This is also being discussed in the usenet newsgroup alt.os.linux.mageia.

I've confirmed the forkbomb will kill my Mageia 2 x86-64 system, with
the default value for nprocs of 127910.  Interestingly, it doesn't kill
the system if I run the forkbomb right after rebooting, only if it's been
in use for a while.  This is a quad core with 16GB of ram.

I've added a line to /etc/security/limits.conf on my system, with
*               hard    nproc           10000

The forkbomb no longer has impact, except for the need to kill all
of the user's bash processes.

# ps -A|wc -l
218

I think 10000 should be more than adequate, yet low enough to stop the
bomb from killing the system.

Regards, Dave Hodgins