Re: [PATCH] mm: __nr_to_section - make it safe against overflow v2

KAMEZAWA Hiroyuki
2009-01-06T06:31:52Z

On Tue, 6 Jan 2009 14:57:41 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> On Mon, 5 Jan 2009 16:37:42 -0800
> Andrew Morton <akpm@linux-foundation.org> wrote:
>
> > On Mon, 5 Jan 2009 13:31:32 +0300
> > Cyrill Gorcunov <gorcunov@gmail.com> 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