linux-kernel - Re: [PATCH][RFC] add MAP

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20091007204718.GD19692@redhat.com>
Date:	Wed, 7 Oct 2009 22:47:18 +0200
From:	Gleb Natapov <gleb@...hat.com>
To:	Olivier Galibert <galibert@...ox.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	linux-api@...r.kernel.org
Subject: Re: [PATCH][RFC] add MAP_UNLOCKED mmap flag

On Wed, Oct 07, 2009 at 10:10:17PM +0200, Olivier Galibert wrote:
> On Wed, Oct 07, 2009 at 08:59:52PM +0200, Gleb Natapov wrote:
> > On Wed, Oct 07, 2009 at 08:50:54PM +0200, Olivier Galibert wrote:
> > > On Tue, Oct 06, 2009 at 02:16:03PM +0200, Gleb Natapov wrote:
> > > > I did. It allows me to achieve something I can't now. Steps you provide
> > > > just don't fit my needs. I need all memory areas (current and feature) to be
> > > > locked except one. Very big one. You propose to lock memory at some
> > > > arbitrary point and from that point on all newly mapped memory areas will
> > > > be unlocked. Don't you see it is different?
> > > 
> > > What about mlockall(MCL_CURRENT); mmap(...); mlockall(MCL_FUTURE);?
> > > Or toggle MCL_FUTURE if a mlockall call can stop it?
> > > 
> > This may work. And MCL_FUTURE can be toggled, but this is not thread
> > safe.
> 
> Just ensure that your one special mmap is done with the other threads
> not currently allocating stuff.  It's probably a synchronization point
> for the whole process anyway.
> 
How can you stop other threads and libraries from calling malloc()? And if
it is two special allocations? Or many mmap(big file)/munmap(big file)?
This is the same issue as opening file CLOEXEC atomically. Why not
prevent other thread from calling fork() instead of adding flags to
bunch of system calls.

--
			Gleb.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/