Subject: Re: CVS commit: src/sys/ufs/lfs
To: Manuel Bouyer <bouyer@antioche.eu.org>
From: David Young <dyoung@pobox.com>
List: source-changes
Date: 03/19/2006 13:44:57
On Sun, Mar 19, 2006 at 02:29:26PM +0100, Manuel Bouyer wrote:
> On Sun, Mar 19, 2006 at 12:58:35PM +0000, Ben Harris wrote:
> > In article <441D4EFD.1010507@omicron-persei-8.net> you write:
> > >YAMAMOTO Takashi wrote:
> > >>what i don't understand here is, why you think NULL initialization is
> > >>better wrt future bugs.
> > >>
> > >>
> > >Would a dereference of the NULL ptr not cause immediate failure?
> >
> > Not necessarily. On older ARM systems, the kernel has a page mapped at
> > address zero containing the CPU vectors. Reading through null pointers
> > works fine, and writing corrupts the vector table, which you'll only
> > find out about when you next take a page fault, interrupt or whatever.
>
> Then maybe NULL should be defined to something else than 0 on those
> platforms ? I wonder how much things will break if we have NULL != 0
> though ...
Lots will break. Both sys/net/ and sys/netinet/ are littered with
'ptr = 0'.
Dave
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