From: Julien TINNES <julien.tinnes.NOSPAM@francetelecom.REMOVE.com>
To: Horst von Brand <vonbrand@inf.utfsm.cl>
Cc: Arjan van de Ven <arjan@infradead.org>, linux-kernel@vger.kernel.org
Subject: Re: Patch 4/6 randomize the stack pointer
Date: Fri, 28 Jan 2005 09:45:53 +0100 [thread overview]
Message-ID: <41F9FBC1.5000204@francetelecom.REMOVE.com> (raw)
In-Reply-To: <200501280203.j0S23Fc8008333@laptop11.inf.utfsm.cl>
Horst von Brand wrote:
> Julien TINNES <julien.tinnes.NOSPAM@francetelecom.REMOVE.com> said:
>
>>Not very important but ((get_random_int() % 4096) << 4) could be
>>optimized into get_random_int() & 0xFFF0.
>
>
> Check first if the compiler doesn't do it by itself.
The compiler cannot guess that get_random_int() gives a random result.
%4096 and & 0xFFF is'nt the same operation. But (get_random_int() %
4096) and (get_random_int() & 0xFFF) gives the same result: a random
number between 0 and 4095, without loss of entropy because 0xFFF has no
0 bit.
--
Julien TINNES - & france telecom - R&D Division/MAPS/NSS
Research Engineer - Internet/Intranet Security
GPG: C050 EF1A 2919 FD87 57C4 DEDD E778 A9F0 14B9 C7D6
next prev parent reply other threads:[~2005-01-28 8:45 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-01-27 10:11 Patch 0/6 virtual address space randomisation Arjan van de Ven
2005-01-27 10:12 ` Patch 1/6 introduce sysctl Arjan van de Ven
2005-01-27 10:36 ` Andi Kleen
2005-01-27 11:13 ` Arjan van de Ven
2005-01-27 18:16 ` Pavel Machek
2005-01-27 19:11 ` Ingo Molnar
2005-01-27 19:46 ` Dave Jones
2005-01-27 19:53 ` Ingo Molnar
2005-01-27 19:53 ` Arjan van de Ven
2005-02-04 21:27 ` Benoit Boissinot
2005-01-27 10:12 ` Patch 2/6 introduce helper infrastructure Arjan van de Ven
2005-01-27 10:41 ` Andi Kleen
2005-01-27 11:58 ` Arjan van de Ven
2005-01-27 12:27 ` Andi Kleen
2005-01-27 12:43 ` Arjan van de Ven
2005-02-01 21:14 ` Matt Mackall
2005-01-27 10:12 ` Patch 3/6 per process flag Arjan van de Ven
2005-01-27 10:13 ` Patch 4/6 randomize the stack pointer Arjan van de Ven
2005-01-27 10:21 ` Christoph Hellwig
2005-01-27 17:38 ` John Richard Moser
2005-01-27 17:47 ` Arjan van de Ven
2005-01-27 18:04 ` John Richard Moser
2005-01-27 18:09 ` Arjan van de Ven
2005-01-27 18:12 ` Christoph Hellwig
2005-01-27 18:16 ` Linus Torvalds
2005-01-27 18:28 ` Linus Torvalds
2005-01-27 18:55 ` John Richard Moser
2005-01-27 18:49 ` John Richard Moser
2005-01-27 19:30 ` Linus Torvalds
2005-01-27 19:48 ` Arjan van de Ven
2005-01-27 19:59 ` Linus Torvalds
2005-01-27 20:04 ` Arjan van de Ven
2005-01-27 20:08 ` John Richard Moser
2005-01-27 19:19 ` linux-os
2005-01-27 19:52 ` Julien TINNES
2005-01-27 20:02 ` Arjan van de Ven
2005-01-27 20:13 ` John Richard Moser
2005-01-27 21:33 ` jnf
2005-01-28 17:22 ` Paulo Marques
2005-01-28 17:51 ` John Richard Moser
2005-01-28 18:42 ` Ingo Molnar
2005-01-29 6:04 ` John Richard Moser
2005-01-27 20:37 ` linux-os
2005-01-27 20:45 ` John Richard Moser
2005-01-27 21:39 ` John Richard Moser
2005-01-27 21:53 ` Arjan van de Ven
2005-01-27 22:34 ` John Richard Moser
2005-01-29 2:50 ` Rik van Riel
2005-01-29 6:31 ` John Richard Moser
2005-01-29 8:10 ` Arjan van de Ven
[not found] ` <41FBB821.3000403@comcast.net>
2005-01-29 16:42 ` Arjan van de Ven
2005-01-29 16:59 ` John Richard Moser
2005-01-29 16:46 ` Arjan van de Ven
2005-01-29 17:04 ` John Richard Moser
2005-01-29 17:37 ` Jakub Jelinek
2005-01-29 17:49 ` John Richard Moser
2005-01-29 17:55 ` Christoph Hellwig
2005-01-29 18:10 ` John Richard Moser
2005-01-29 18:12 ` Rik van Riel
2005-01-29 18:16 ` Christoph Hellwig
2005-01-29 7:46 ` John Richard Moser
2005-01-27 18:40 ` Felipe Alfaro Solana
2005-01-27 22:31 ` Jirka Kosina
2005-01-28 5:58 ` Ingo Molnar
2005-01-28 19:02 ` David Lang
2005-01-28 7:33 ` Arjan van de Ven
2005-01-27 19:43 ` Julien TINNES
2005-01-28 0:10 ` H. Peter Anvin
2005-01-28 0:23 ` Roland Dreier
2005-01-28 1:06 ` H. Peter Anvin
2005-01-28 2:03 ` Horst von Brand
2005-01-28 8:45 ` Julien TINNES [this message]
2005-01-27 20:23 ` Christoph Hellwig
2005-01-27 20:27 ` Arjan van de Ven
2005-01-27 20:32 ` Christoph Hellwig
2005-01-27 20:35 ` Arjan van de Ven
2005-01-27 20:40 ` Rik van Riel
2005-01-27 20:42 ` Christoph Hellwig
2005-01-27 20:56 ` Arjan van de Ven
2005-01-27 21:13 ` Linus Torvalds
2005-01-27 10:13 ` Patch 5/6 randomize mmap addresses Arjan van de Ven
2005-01-27 10:14 ` Patch 6/6 default enable randomisation for -mm Arjan van de Ven
2005-01-27 11:45 ` Patch 0/6 virtual address space randomisation Julien TINNES
2005-01-27 11:57 ` Arjan van de Ven
2005-01-27 17:42 ` John Richard Moser
2005-01-27 19:34 ` Julien TINNES
2005-01-27 19:57 ` John Richard Moser
2005-01-27 20:13 ` Arjan van de Ven
2005-01-28 8:45 ` David Weinehall
-- strict thread matches above, loose matches on Subject: below --
2005-01-31 10:55 Patch 4/6 randomize the stack pointer linux
2005-01-31 17:28 ` John Richard Moser
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