[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Sat, 3 Mar 2018 18:13:28 +0300
From: Ilya Smith <blackzert@...il.com>
To: Matthew Wilcox <willy@...radead.org>
Cc: Kees Cook <keescook@...omium.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Dan Williams <dan.j.williams@...el.com>,
Michal Hocko <mhocko@...e.com>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Jan Kara <jack@...e.cz>, Jerome Glisse <jglisse@...hat.com>,
Hugh Dickins <hughd@...gle.com>, Helge Deller <deller@....de>,
Andrea Arcangeli <aarcange@...hat.com>,
Oleg Nesterov <oleg@...hat.com>, Linux-MM <linux-mm@...ck.org>,
LKML <linux-kernel@...r.kernel.org>,
Kernel Hardening <kernel-hardening@...ts.openwall.com>
Subject: Re: [RFC PATCH] Randomization of address chosen by mmap.
> On 2 Mar 2018, at 23:48, Matthew Wilcox <willy@...radead.org> wrote:
> Ah, I didn't mean that. I was thinking that we can change the
> implementation to reserve 1-N pages after the end of the mapping.
> So you can't map anything else in there, and any load/store into that
> region will segfault.
>
I’m afraid it still will allow many attacks. The formula for new address would
be like: address_next = address_prev - mmap_size - random(N) as you suggested.
To prevent brute-force attacks N should be big enough like more 2^32 for
example. This number 2^32 is just an example and right now I don’t know the
exact value. What I’m trying to say that address computation formula has
dependency on concrete predictable address. In my scheme even address_prev was
chose randomly.
Best regards,
Ilya
Powered by blists - more mailing lists