From: Rusty Russell <rusty@rustcorp.com.au>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Jamie Lokier <lk@tantalophile.demon.co.uk>,
"Perez-Gonzalez, Inaky" <inaky.perez-gonzalez@intel.com>,
"'Mark Mielke'" <mark@mark.mielke.cc>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Users locking memory using futexes
Date: Wed, 13 Nov 2002 05:13:35 +1100 [thread overview]
Message-ID: <20021113071630.376412C118@lists.samba.org> (raw)
In-Reply-To: Your message of "12 Nov 2002 18:06:24 -0000." <1037124384.8321.70.camel@irongate.swansea.linux.org.uk>
In message <1037124384.8321.70.camel@irongate.swansea.linux.org.uk> you write:
> 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 havie nasty accidents with than pipes.
It's bounded by one page per fd. If you want better than that, then
yes we'll need to thihk harder.
Frobbing futexes on COW and page-in/out is a possible solution, but
requires careful thought.
Rusty.
--
Anyone who quotes me in their sig is an idiot. -- Rusty Russell.
next prev parent reply other threads:[~2002-11-13 7:09 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-11-11 20:28 PROT_SEM + FUTEX Perez-Gonzalez, Inaky
2002-11-11 21:46 ` Mark Mielke
2002-11-12 3:46 ` Users locking memory using futexes Jamie Lokier
2002-11-12 17:17 ` Rusty Russell
2002-11-12 18:06 ` Alan Cox
2002-11-12 18:13 ` Rusty Russell [this message]
2002-11-13 14:27 ` Alan Cox
-- strict thread matches above, loose matches on Subject: below --
2002-11-12 4:16 Perez-Gonzalez, Inaky
2002-11-12 5:21 ` Jamie Lokier
2002-11-12 9:11 ` Ingo Molnar
2002-11-12 17:40 ` Jamie Lokier
2002-11-12 5:56 Perez-Gonzalez, Inaky
2002-11-12 17:36 ` Jamie Lokier
2002-11-12 17:57 Perez-Gonzalez, Inaky
2002-11-12 19:17 ` Jamie Lokier
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