linux-kernel - Re: mmap: is default non-populating behavior stable?

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <49107D98.9080201@gmail.com>
Date:	Tue, 04 Nov 2008 18:51:36 +0200
From:	"Eugene V. Lyubimkin" <jackyf.devel@...il.com>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
CC:	Peter Zijlstra <peterz@...radead.org>,
	Chris Friesen <cfriesen@...tel.com>,
	Rik van Riel <riel@...hat.com>, linux-kernel@...r.kernel.org,
	linux-mm <linux-mm@...ck.org>, hugh <hugh@...itas.com>
Subject: Re: mmap: is default non-populating behavior stable?

Alan Cox wrote:
> On Tue, 04 Nov 2008 17:07:00 +0100
> Peter Zijlstra <peterz@...radead.org> wrote:
>> [snip]
>> I'm not sure how POSIX speaks of this.
>>
>> I think Linux does the expected thing.
> 
> I believe our behaviour is correct for mmap/mumap/truncate and it
> certainly used to be and was tested.
> 
> At the point you do anything involving mremap (which is non posix) our
> behaviour becomes rather bizarre.

Thanks to all for answers. I have made the conclusion that doing "open() new
file, truncate(<big size>), mmap(<the same big size>), write/read some memory
pages" should not populate other, untouched by write/read pages (until
MAP_POPULATE given), right?

-- 
Eugene V. Lyubimkin aka JackYF


Download attachment "signature.asc" of type "application/pgp-signature" (261 bytes)