/proc/sys/vm/mmap_min_addr missing

[Baruch Siach]

Hi Valery,

On Tue, Jan 15, 2013 at 12:42:33AM -0800, Valery Reznic wrote:
> ----- Original Message -----
> > From: Baruch Siach <baruch at tkos.co.il>
> > To: Valery Reznic <valery_reznic at yahoo.com>
> > Cc: shimi <linux-il at shimi.net>; linux-il <linux-il at cs.huji.ac.il>
> > Sent: Tuesday, January 15, 2013 9:33 AM
> > Subject: Re: /proc/sys/vm/mmap_min_addr missing
> > 
> > On Mon, Jan 14, 2013 at 11:24:27PM -0800, Valery Reznic wrote:
> >>  > From: shimi <linux-il at shimi.net>
> >>  >To: Valery Reznic <valery_reznic at yahoo.com> 
> >>  >Cc: linux-il <linux-il at cs.huji.ac.il> 
> >>  >Sent: Tuesday, January 15, 2013 6:21 AM
> >>  >Subject: Re: /proc/sys/vm/mmap_min_addr missing
> >>  > 
> >>  >
> >>  >On Mon, Jan 14, 2013 at 11:40 PM, Valery Reznic 
> > <valery_reznic at yahoo.com> wrote:
> >>  >
> >>  >Recently I stumbled upon some mystery that I can't understand.
> >>  >>My Google search bring no results.
> >>  >>
> >>  >>I have 3 VM with different Linuxes that run under QEMU and now I 
> > noticed that
> >>  >>all of them don't have /proc/sys/vm/mmap_min_addr files (/proc 
> > is mounted)
> >>  > 
> >>  >Are you emulating ARM on the guests by any chance?
> >>  I am running Fedora 12 ARM, Fedora Core 3 x86-64, and debian ARM
> >>  I don't remember debian version, but it's ARM OABI
> > 
> > mmap_min_addr first appeared in kernel version 2.6.23, commit ed032189 
> > (security: Protection for exploiting null dereference using mmap). What kernel 
> > versions are you running in your virtualized machines?
> My host with Fedora 12 x86-64
> Linux Fedora8 2.6.32.26-175.fc12.x86_64 #1 SMP Wed Dec 1 21:39:34 UTC 2010 x86_64 x86_64 x86_64 GNU/Linux
> 
> has mmap_min_addr

No problem here.

> Fedora 3 x86-64 with kernel 2.6.9-1.667 also has not mmap_min_addr

No problem here either (kernel too old).

> Fedora 12 ARM with kernel 
> 
> uname -a
> Linux fedora-arm 2.6.24-rc7 #1 Wed Jan 16 02:28:08 CET 2008 armv5tel armv5tel armv5tel GNU/Linux
> 
> has not

I now see that the original commit (ed032189) made mmap_min_addr depend on 
CONFIG_SECURITY. Do you have this enabled in your kernel configuration?

> Debian ARM OABI I think, has kernel 2.4 (can't check it now)

baruch

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