From: Larry McVoy <lm@bitmover.com>
To: Linus Torvalds <torvalds@transmeta.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>,
linux-kernel@vger.kernel.org, alan@lxorguk.ukuu.org.uk
Subject: Re: AUDIT: copy_from_user is a deathtrap.
Date: Sat, 18 May 2002 20:05:40 -0700 [thread overview]
Message-ID: <20020518200540.N8794@work.bitmover.com> (raw)
In-Reply-To: <E179GA4-0004ZT-00@wagner.rustcorp.com.au> <Pine.LNX.4.44.0205181958140.30454-100000@home.transmeta.com>
On Sat, May 18, 2002 at 08:01:48PM -0700, Linus Torvalds wrote:
> On Sun, 19 May 2002, Rusty Russell wrote:
> >
> > Huh? No, you ask for 2000 bytes into a buffer that can only take 1000
> > bytes without hitting an unmapped page, returning EFAULT or giving a
> > SIGSEGV is perfectly acceptable.
>
> Bzzt, wrong answer.
Linus is absolutely right. The correct semantics are to return the number
of bytes read, if they are greater than zero, and on the next read return
the error. This has been a corner case in read for a long time in various
Unix versions, and Linus has it right. I went through this back at Sun
and we explored all the different ways, and the bottom line is that you
first ACK that you moved some data and then you NAK on the next read.
--
---
Larry McVoy lm at bitmover.com http://www.bitmover.com/lm
next prev parent reply other threads:[~2002-05-19 3:05 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <E178eMm-0000NO-00@wagner.rustcorp.com.au.suse.lists.linux.kernel>
[not found] ` <Pine.LNX.4.44.0205171936220.1524-100000@home.transmeta.com.suse.lists.linux.kernel>
2002-05-18 10:16 ` AUDIT: copy_from_user is a deathtrap Andi Kleen
2002-05-18 16:14 ` Linus Torvalds
2002-05-19 2:10 ` Rusty Russell
2002-05-19 3:01 ` Linus Torvalds
2002-05-19 3:05 ` Larry McVoy [this message]
2002-05-19 4:01 ` Rusty Russell
2002-05-19 4:02 ` Larry McVoy
2002-05-16 23:56 ` Pavel Machek
2002-05-16 23:56 ` Pavel Machek
2002-05-19 3:31 ` Rusty Russell
2002-05-19 3:34 ` Linus Torvalds
2002-05-16 23:53 ` Pavel Machek
2002-05-21 20:47 ` Linus Torvalds
2002-05-21 21:17 ` Pavel Machek
2002-05-21 21:25 ` Linus Torvalds
2002-05-21 21:44 ` Alan Cox
2002-05-21 21:46 ` Andrew Morton
2002-05-21 22:04 ` Linus Torvalds
2002-05-21 22:21 ` Pavel Machek
2002-05-22 13:47 ` Alan Cox
2002-05-22 14:13 ` Pavel Machek
2002-05-22 14:54 ` Alan Cox
2002-05-22 14:42 ` Pavel Machek
2002-05-22 15:27 ` Alan Cox
2002-05-22 18:58 ` Kasper Dupont
2002-05-22 22:02 ` Alan Cox
2002-05-23 3:54 ` Rusty Russell
2002-05-23 11:15 ` Edgar Toernig
2002-05-22 16:09 ` Linus Torvalds
2002-05-22 20:28 ` Pavel Machek
2002-05-22 0:47 ` Andrea Arcangeli
2002-05-22 5:01 ` Rusty Russell
2002-05-22 6:28 ` Rusty Russell
2002-05-22 4:57 ` Rusty Russell
2002-05-22 13:30 ` Alan Cox
2002-05-22 18:43 ` Marco Colombo
2002-05-19 20:23 ` Edgar Toernig
2002-05-19 22:44 ` Alan Cox
2002-05-22 13:40 Petr Vandrovec
2002-05-22 18:58 ` Denis Vlasenko
2002-05-22 14:13 ` Ruth Ivimey-Cook
-- strict thread matches above, loose matches on Subject: below --
2002-05-22 10:08 Petr Vandrovec
2002-05-22 16:23 ` Denis Vlasenko
[not found] <Pine.LNX.4.44.0205191951460.22433-100000@home.transmeta.com.suse.lists.linux.kernel>
[not found] ` <E179fAd-0005vs-00@wagner.rustcorp.com.au.suse.lists.linux.kernel>
2002-05-20 10:59 ` Andi Kleen
2002-05-19 3:38 Rusty Russell
2002-05-19 5:23 ` Linus Torvalds
2002-05-17 0:00 ` Pavel Machek
2002-05-18 21:47 ` Benjamin Herrenschmidt
2002-05-19 12:22 ` Alan Cox
2002-05-19 18:29 ` Linus Torvalds
2002-05-19 19:57 ` Roman Zippel
2002-05-20 2:06 ` Rusty Russell
2002-05-20 2:54 ` Linus Torvalds
2002-05-20 4:53 ` Rusty Russell
2002-05-19 20:12 ` Arnaldo Carvalho de Melo
2002-05-20 16:00 ` Linus Torvalds
2002-05-19 11:41 ` Alan Cox
[not found] <mailman.1021642692.12772.linux-kernel2news@redhat.com>
2002-05-17 17:36 ` Pete Zaitcev
2002-05-18 1:05 ` Rusty Russell
2002-05-18 2:57 ` Alan Cox
2002-05-16 23:27 ` Pavel Machek
[not found] ` <200205191212.g4JCCLY25867@Port.imtp.ilyichevsk.odessa.ua>
[not found] ` <20020520112232.A8983@devserv.devel.redhat.com>
2002-05-21 10:57 ` Denis Vlasenko
2002-05-21 6:21 ` Arnaldo Carvalho de Melo
2002-05-21 8:33 ` Christoph Hellwig
2002-05-21 19:02 ` Albert D. Cahalan
2002-05-22 14:27 ` Denis Vlasenko
2002-05-17 9:27 Rusty Russell
2002-05-17 9:21 ` David S. Miller
2002-05-17 9:49 ` Rusty Russell
2002-05-17 9:35 ` David S. Miller
2002-05-17 12:26 ` Rusty Russell
2002-05-17 17:42 ` Denis Vlasenko
2002-05-17 12:17 ` Alan Cox
2002-05-17 12:21 ` Rusty Russell
2002-05-17 12:58 ` Alan Cox
2002-05-17 12:58 ` Rusty Russell
2002-05-17 13:13 ` John Levon
2002-05-17 14:52 ` Alan Cox
2002-05-18 1:26 ` Rusty Russell
2002-05-17 17:58 ` Denis Vlasenko
2002-05-18 2:37 ` Linus Torvalds
2002-05-18 15:06 ` John Alvord
2002-05-17 10:20 ` Christoph Hellwig
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