Re: [PATCH] mm: __nr_to_section - make it safe against overflow v2
From: KAMEZAWA Hiroyuki
Date: Tue Jan 06 2009 - 01:31:53 EST
On Tue, 6 Jan 2009 14:57:41 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
> On Mon, 5 Jan 2009 16:37:42 -0800
> Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> > On Mon, 5 Jan 2009 13:31:32 +0300
> > Cyrill Gorcunov <gorcunov@xxxxxxxxx> wrote:
> >
> > > __nr_to_section should check for array bound overflow.
> > > We should better get NULL dereference then silently
> > > pass some memory snippet out of bounds to a caller.
> > >
> >
> > Are there actually any known problems here?
> >
>
> IIRC, I never saw any problem. (But I may see in memory-hotplug development.)
I digged mails and seems this patch is from this thread.
=
http://lkml.org/lkml/2009/1/4/61
=
He seems to want to hunt boot time failure.
(Finally, BIOS-update was necessary for original problem of this thread.)
Cyrill, could you modify this WARN_ON() works works when __nr_to_section()
is called directly by sparse.c and memhotplug.c ?
Adding WARN_ON() in pfn_to_page() is overkill.
Thanks,
-Kame
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