Re: [patch 0/5] Support for sanitization flag in low-level page allocator

Ingo Molnar
2009-05-30T22:14:46Z

* Pekka Enberg <penberg@cs.helsinki.fi> wrote:

> Hi Larry,
>
> On Sat, May 30, 2009 at 9:03 PM, Larry H. <research@subreption.com> wrote:
> > The first issue is that SLOB has a broken ksize, which won't take into
> > consideration compound pages AFAIK. To fix this you will need to
> > introduce some changes in the way the slob_page structure is handled,
> > and add real size tracking to it. You will find these problems if you
> > try to implement a reliable kmem_ptr_validate for SLOB, too.
>
> Does this mean that kzfree() isn't broken for SLAB/SLUB? Maybe I
> read your emails wrong but you seemed to imply that.

Yep, he definitely wrote that:

http://lkml.org/lkml/2009/5/30/30

[...]
|
| That's hopeless, and kzfree is broken. Like I said in my earlier
| reply, please test that yourself to see the results. Whoever
| wrote that ignored how SLAB/SLUB work and if kzfree had been used
| somewhere in the kernel before, it should have been noticed long
| time ago.
|
[...]

Very puzzling claims i have to say.

Ingo