Re: [PATCH 07/11] Memory compaction core

[Jonathan Corbet]

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

> > > 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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/