From: Chris Friesen <cfriesen@nortelnetworks.com>
To: linux-os@analogic.com
Cc: Bryn Reeves <breeves@redhat.com>, Rik van Riel <riel@redhat.com>,
Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org,
James Antill <james.antill@redhat.com>
Subject: Re: don't let mmap allocate down to zero
Date: Wed, 26 Jan 2005 13:13:11 -0600 [thread overview]
Message-ID: <41F7EBC7.5030108@nortelnetworks.com> (raw)
In-Reply-To: <Pine.LNX.4.61.0501261325540.18301@chaos.analogic.com>
linux-os wrote:
> The seg-fault you get when you de-reference a pointer to NULL
> is caused by the kernel. You are attempting to access memory
> that has not been mapped into your address space. Once that
> memory gets mmap()ed, you will no longer get a seg-fault.
> Again, the seg-fault has nothing to do with 'C'. It's an
> implementation behavior that can be changed with mmap().
The segfault *does* have something to do with C. The standard says that
the result of dereferencing a NULL pointer is *undefined*. Not
implementation-defined, but undefined. Anything relying on
dereferencing NULL pointers is not valid C code.
Chris
next prev parent reply other threads:[~2005-01-27 2:01 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-01-26 16:18 don't let mmap allocate down to zero Rik van Riel
2005-01-26 16:38 ` linux-os
2005-01-26 17:05 ` Sytse Wielinga
2005-01-26 17:34 ` Chris Friesen
2005-01-26 17:57 ` Bryn Reeves
2005-01-26 18:37 ` linux-os
2005-01-26 18:54 ` Rik van Riel
2005-01-26 19:09 ` linux-os
2005-01-26 19:13 ` Chris Friesen [this message]
2005-01-26 19:08 ` Chris Friesen
2005-01-26 18:10 ` Olivier Galibert
2005-01-26 18:20 ` linux-os
2005-01-26 18:31 ` Olivier Galibert
2005-01-26 18:39 ` linux-os
2005-01-26 19:41 ` Arjan van de Ven
2005-01-26 20:26 ` Andy Isaacson
2005-01-26 20:42 ` Rik van Riel
2005-01-26 22:12 ` Kyle Moffett
2005-01-26 23:31 ` Brian Gerst
2005-01-26 17:25 ` William Lee Irwin III
2005-01-27 5:09 ` William Lee Irwin III
2005-01-27 5:18 ` Dave Jones
2005-01-27 5:28 ` William Lee Irwin III
2005-01-27 9:29 ` Mikael Pettersson
2005-01-27 12:52 ` William Lee Irwin III
2005-01-27 14:25 ` Russell King
2005-01-27 15:12 ` William Lee Irwin III
2005-01-27 19:22 ` Rik van Riel
2005-01-27 20:44 ` William Lee Irwin III
2005-01-27 20:58 ` Rik van Riel
2005-01-27 21:13 ` William Lee Irwin III
2005-01-27 21:28 ` Rik van Riel
2005-01-28 5:30 ` William Lee Irwin III
2005-01-28 13:01 ` Rik van Riel
2005-01-28 14:14 ` Hugh Dickins
2005-01-28 14:26 ` William Lee Irwin III
2005-01-28 15:41 ` Rik van Riel
2005-01-28 15:53 ` Hugh Dickins
2005-01-27 21:58 ` linux-os
2005-01-27 14:26 ` Mikael Pettersson
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