From: Russell King <rmk+lkml@arm.linux.org.uk>
To: Jamie Lokier <jamie@shareable.org>
Cc: William Lee Irwin III <wli@holomorphy.com>,
linux-kernel@vger.kernel.org,
Michael Kerrisk <michael.kerrisk@gmx.net>
Subject: Re: Testing PROT_NONE and other protections, and a surprise
Date: Thu, 1 Jul 2004 13:52:58 +0100 [thread overview]
Message-ID: <20040701135258.A5225@flint.arm.linux.org.uk> (raw)
In-Reply-To: <20040701032606.GA1564@mail.shareable.org>; from jamie@shareable.org on Thu, Jul 01, 2004 at 04:26:06AM +0100
On Thu, Jul 01, 2004 at 04:26:06AM +0100, Jamie Lokier wrote:
> When running it on i386, I got a *huge* surprise (to me). A
> PROT_WRITE-only page can sometimes fault on read or exec. This is the
> output:
>
> Requested PROT | --- R-- -W- RW- --X R-X -WX RWX
> ========================================================================
> MAP_SHARED | --- r-x !w! rwx r-x r-x rwx rwx
> MAP_PRIVATE | --- r-x !w! rwx r-x r-x rwx rwx
>
> The "!" means that a read or exec *sometimes* raises a signal.
Here are the ARM results:
Requested PROT | --- R-- -W- RW- --X R-X -WX RWX
========================================================================
MAP_SHARED | --- r-x !w! rwx r-x r-x rwx rwx
MAP_PRIVATE | --- r-x !w! rwx r-x r-x rwx rwx
As expected, the same as x86 since we have the same situation there -
we can not represent the write-only page permission in hardware.
--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/
2.6 Serial core
next prev parent reply other threads:[~2004-07-01 12:53 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-06-30 2:44 A question about PROT_NONE on ARM and ARM26 Jamie Lokier
2004-06-30 3:38 ` William Lee Irwin III
2004-07-01 3:26 ` Testing PROT_NONE and other protections, and a surprise Jamie Lokier
2004-07-01 3:35 ` William Lee Irwin III
2004-07-01 4:01 ` Jamie Lokier
2004-07-01 3:44 ` Kyle Moffett
2004-07-01 4:11 ` Jamie Lokier
2004-07-01 4:59 ` Kyle Moffett
2004-07-01 12:39 ` Jamie Lokier
2004-07-01 14:43 ` [OT] " Kyle Moffett
2004-07-01 14:50 ` Jamie Lokier
2004-07-01 15:01 ` Kyle Moffett
2004-07-01 16:37 ` Matt Mackall
2004-07-01 17:26 ` Michael Driscoll
2004-07-02 7:37 ` Gabriel Paubert
2004-07-01 12:52 ` Russell King [this message]
2004-07-01 14:26 ` Richard Curnow
2004-06-30 8:16 ` A question about PROT_NONE on ARM and ARM26 Russell King
2004-06-30 14:59 ` Jamie Lokier
2004-06-30 15:22 ` Ian Molton
2004-06-30 18:26 ` Russell King
2004-06-30 19:14 ` Jamie Lokier
2004-06-30 19:23 ` Russell King
2004-06-30 20:15 ` Jamie Lokier
2004-06-30 22:59 ` Russell King
2004-06-30 23:30 ` Jamie Lokier
2004-06-30 23:48 ` Ian Molton
2004-07-01 1:59 ` Jamie Lokier
2004-07-01 1:05 ` Nicolas Pitre
2004-07-01 1:50 ` Jamie Lokier
2004-07-02 18:39 ` Russell King
2004-07-01 15:27 ` Scott Wood
2004-07-01 23:53 ` Jamie Lokier
2004-07-02 14:36 ` Scott Wood
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