Re: [patch] mm: sparsemem memory_present() memory corruption fix

From: Yinghai Lu
Date: Tue Apr 15 2008 - 22:00:44 EST


On Tue, Apr 15, 2008 at 6:30 PM, Yinghai Lu <yhlu.kernel@xxxxxxxxx> wrote:
>
> On Tue, Apr 15, 2008 at 6:17 PM, Ingo Molnar <mingo@xxxxxxx> wrote:
> >
> > * Ingo Molnar <mingo@xxxxxxx> wrote:
> >
> > > > > this is the only call to memory_present() we do in 32-bit arch
> > > > > setup, so it's required.
> > > >
> > > > We could clip there if SPARSEMEM is configured. I wonder if this
> > > > affects other platforms that need HIGHMEM support?
> > >
> > > clip where and what?
> >
> > i.e. as per my previous argument i'd consider the need to sanitize the
> > calls in the architecture fundamentally wrong.
> >
> > whether the core code emits a warning or allows the call is an
> > additional question i mention in the changelog - but the core sparse
> > memory code should _definitely_ not silently overflow a key internal
> > array ... (of which data structure the architecture code is not even
> > aware of)
>
> or you can move that check into find_max_pfn for x86_32? so it will
> not affect other platform regarding Christoph's concern?
>
the patch doesn't have side effects on x86_64.

YH
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