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Subject: Re: Users locking memory using futexes
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jamie Lokier <lk@tantalophile.demon.co.uk>,
       "Perez-Gonzalez, Inaky" <inaky.perez-gonzalez@intel.com>,
       "'Mark Mielke'" <mark@mark.mielke.cc>,
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On Tue, 2002-11-12 at 17:17, Rusty Russell wrote:
> > Ouch!  It looks to me like userspace can use FUTEX_FD to lock many
> > pages of memory, achieving the same as mlock() but without the
> > resource checks.
> > 
> > Denial of service attack?
> 
> See "pipe".

Thats not an excuse. If the futex stuff allows arbitary memory locking
and it isnt properly accounted then its a bug, with the added problem
that its easier to have nasty accidents with than pipes.

We have a per user object nowdays so accounting per user locked memory
looks rather doable both for mlock, pipe, af_unix socket and for other
things

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