On Wed, 24 Mar 2010 22:19:24 +0100
Andrea Arcangeli <aarcange@redhat.com> wrote:

quoted text
> > > It's a bit strange to test this when we're about to oops anyway.  The
> > > oops will tell us the same thing.  
> > 
> > ...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...?  
> 
> Examples? Maybe WARN_ON != oops, but VM_BUG_ON still an oops that is
> and without serial console it would go lost too. I personally don't
> see how it's needed.

I don't quite understand the question; are you asking for examples of
exploits?

	http://lwn.net/Articles/347006/
	http://lwn.net/Articles/360328/
	http://lwn.net/Articles/342330/
	...

As to whether this particular test makes sense, I don't know.  But the
idea that we never need to test about-to-be-dereferenced pointers for
NULL does worry me a bit.

jon
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