Re: [PATCH] kernel buffer overflow kmalloc_slab() fix

[J Freyensee <james_p_freyensee@linux.intel.com>]

On Thu, 2011-05-19 at 15:51 -0500, Christoph Lameter wrote:
> On Thu, 19 May 2011, james_p_freyensee@linux.intel.com wrote:
> 
> > From: J Freyensee <james_p_freyensee@linux.intel.com>
> >
> > Currently, kmalloc_index() can return -1, which can be
> > passed right to the kmalloc_caches[] array, cause a
> 
> No kmalloc_index() cannot return -1 for the use case that you are
> considering here. The value passed as a size to
> kmalloc_slab is bounded by 2 * PAGE_SIZE and kmalloc_slab will only return
> -1 for sizes > 4M. So we will have to get machines with page sizes > 2M
> before this can be triggered.
> 
> 

Okay.  I thought it would still be good to check for -1 anyways, even if
machines today cannot go above 2M page sizes.  I would think it would be
better for software code to always make sure a case that this could
never happen instead of relying on whatever physical hardware limits the
linux kernel could be running on on today's machines or future machines,
because technology has shown limits can change.  I would think
regardless what this code runs on, this is still a software flaw that
can be considered not a good thing to allow lying around in software
code that can easily be fixed.

But again I'm fine with whatever is decided. 


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