Follow @Openwall on Twitter for new release announcements and other news
[<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

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.