linux-kernel - Re: [PATCH 2/2] mm/mmap.c: do not allow mappings outside of allowed limits

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Message-Id: <20200421052945.GA26279@oc3871087118.ibm.com>
Date:   Tue, 21 Apr 2020 07:29:46 +0200
From:   Alexander Gordeev <agordeev@...ux.ibm.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 2/2] mm/mmap.c: do not allow mappings outside of allowed
 limits

On Mon, Apr 20, 2020 at 07:59:03PM -0700, Andrew Morton wrote:
> On Mon, 23 Mar 2020 14:29:29 +0100 agordeev@...ux.ibm.com wrote:
> 
> > It is possible to request a fixed mapping address below
> > mmap_min_addr and succeed. This update adds early checks
> > of mmap_min_addr and mmap_end boundaries and fixes the
> > above issue.
> 
> Does this solve any known problems?  If not, what is the motivation for
> the change?

One can set a lowest possible address in /proc/sys/vm/mmap_min_addr 
and mmap below that bound nevertheless. Apart from it is wrong I am
not aware of any existing issue.

Thanks!