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From: Joseph Myers <joseph@codesourcery.com>
To: Florian Weimer <fweimer@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
	Topi Miettinen <toiwoton@gmail.com>,
	<linux-hardening@vger.kernel.org>, <akpm@linux-foundation.org>,
	<linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
	Jann Horn <jannh@google.com>, Kees Cook <keescook@chromium.org>,
	Matthew Wilcox <willy@infradead.org>,
	Mike Rapoport <rppt@kernel.org>,
	Linux API <linux-api@vger.kernel.org>
Subject: Re: [PATCH v5] mm: Optional full ASLR for mmap(), mremap(), vdso and stack
Date: Thu, 3 Dec 2020 19:26:25 +0000	[thread overview]
Message-ID: <alpine.DEB.2.22.394.2012031918220.193081@digraph.polyomino.org.uk> (raw)
In-Reply-To: <871rg6yf1i.fsf@oldenburg2.str.redhat.com>

On Thu, 3 Dec 2020, Florian Weimer wrote:

> My knowledge of probability theory is quite limited, so I have to rely
> on simulations.  But I think you would see a 40 GiB gap somewhere for a
> 47-bit address space with 32K allocations, most of the time.  Which is
> not too bad.

This is very close to a Poisson process (if the number of small 
allocations being distributed independently in the address space is 
large), so the probability that any given gap is at least x times the mean 
gap is about exp(-x).

-- 
Joseph S. Myers
joseph@codesourcery.com

      parent reply	other threads:[~2020-12-03 19:27 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-29 21:15 [PATCH v5] mm: Optional full ASLR for mmap(), mremap(), vdso and stack Topi Miettinen
2020-11-30  6:08 ` kernel test robot
2020-11-30 17:57 ` Andy Lutomirski
2020-11-30 20:27   ` Topi Miettinen
2020-12-03  9:47 ` Florian Weimer
2020-12-03 12:02   ` Topi Miettinen
2020-12-03 17:10     ` Andy Lutomirski
2020-12-03 17:28       ` Florian Weimer
2020-12-03 17:42         ` Andy Lutomirski
2020-12-03 18:00           ` Matthew Wilcox
2020-12-03 19:26         ` Joseph Myers [this message]

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