Re: [PATCH 07/11] Memory compaction core

[Christoph Lameter]

On Wed, 24 Mar 2010, Andrew Morton wrote:

> > ...except that we've seen a fair number of null pointer dereference
> > exploits that have told us something altogether different.  Are we
> > *sure* we don't want to test for null pointers...?
> >
>
> It's hard to see what the test gains us really - the kernel has
> zillions of pointer derefs, any of which could be NULL if we have a
> bug.  Are we more likely to have a bug here than elsewhere?
>
> This one will oops on a plain old read, so it's a bit moot in this
> case.

If the object pointed to is larger than page size and we are
referencing a member with an offset larger than page size later then we
may create an exploit without checks.

But the structure here is certainly smaller than that. So no issue here.



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