From: Pavel Machek <pavel@suse.cz>
To: Manfred Spraul <manfred@colorfullife.com>
Cc: Kasper Dupont <kasperd@daimi.au.dk>,
"David S. Miller" <davem@redhat.com>,
rusty@rustcorp.com.au, linux-kernel@vger.kernel.org
Subject: Re: [TRIVIAL] Warn users about machines with non-working WP bit
Date: Mon, 20 Aug 2001 20:06:49 +0000 [thread overview]
Message-ID: <20010820200648.B111@toy.ucw.cz> (raw)
In-Reply-To: <3D4FDEF3.8070207@colorfullife.com>; from manfred@colorfullife.com on Tue, Aug 06, 2002 at 04:36:35PM +0200
Hi!
> >I just get another idea, that might be easier to get right. If
> >the only problem is one process changing the mm while another
> >process is doing a copy_to_user, we should be able to fix it by
> >placing a readlock on the mm while the copy_to_user is in progress.
> >
> >
> Yes, that would work. copy_to_user is never called with the mmap
> semaphore locked, i.e.
>
> #define copy_to_user(...) > down(¤t->mm->mmap_sem); > check_wp_bit(); > real_copy_to_user(); > up(¤t->mm->mmap_sem)
>
> verify_area would just check that the pointer is below TASK_SIZE, and
> the wp bit is checked within copy_to_user().
>
> But how many 80386 Linux systems that run the 2.4 kernel exist?
Many embedded boxes, I beieve, have modern 386 CPUs.
Pavel
--
Philips Velo 1: 1"x4"x8", 300gram, 60, 12MB, 40bogomips, linux, mutt,
details at http://atrey.karlin.mff.cuni.cz/~pavel/velo/index.html.
next prev parent reply other threads:[~2002-08-19 20:30 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-08-06 9:17 Manfred Spraul
2002-08-06 9:28 ` David S. Miller
2002-08-06 9:42 ` Manfred Spraul
2001-08-20 20:03 ` Pavel Machek
2002-08-06 14:03 ` Kasper Dupont
2002-08-06 13:56 ` David S. Miller
2002-08-06 14:16 ` Kasper Dupont
2002-08-06 14:05 ` David S. Miller
2002-08-06 14:27 ` Kasper Dupont
2002-08-06 14:36 ` Manfred Spraul
2001-08-20 20:06 ` Pavel Machek [this message]
2002-08-19 22:04 ` Alan Cox
2002-08-06 15:11 ` Kasper Dupont
2002-08-06 16:38 ` Willy Tarreau
2002-08-06 16:45 ` Zwane Mwaikambo
-- strict thread matches above, loose matches on Subject: below --
2002-08-06 3:49 Rusty Trivial Russell
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