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Groups > linux.kernel > #1327547

Re: [PATCH] mm/slub: support left red zone

From Christoph Lameter <cl@linux.com>
Newsgroups linux.kernel
Subject Re: [PATCH] mm/slub: support left red zone
Date 2016-02-05 10:10 +0100
Message-ID <qYKyS-6DW-21@gated-at.bofh.it> (permalink)
References <qYlqO-4PS-19@gated-at.bofh.it> <qYlAt-4SU-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Thu, 4 Feb 2016, Joonsoo Kim wrote:

> On Thu, Feb 04, 2016 at 03:15:50PM +0900, Joonsoo Kim wrote:
> > SLUB already has red zone debugging feature. But, it is only positioned
> > at the end of object(aka right red zone) so it cannot catch left oob.
> > Although current object's right red zone acts as left red zone of
> > previous object, first object in a slab cannot take advantage of
>
> Oops... s/previous/next.
>
> > this effect. This patch explicitly add left red zone to each objects
> > to detect left oob more precisely.


An access before the first object is an access outside of the page
boundaries of a page allocated by the page allocator for the slab
allocator since the first object starts at offset 0.



And the page allocator debugging methods can catch that case.


Do we really need this code?

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Thread

[PATCH] mm/slub: support left red zone Joonsoo Kim <js1304@gmail.com> - 2016-02-04 07:20 +0100
  Re: [PATCH] mm/slub: support left red zone Joonsoo Kim <iamjoonsoo.kim@lge.com> - 2016-02-04 07:30 +0100
    Re: [PATCH] mm/slub: support left red zone Christoph Lameter <cl@linux.com> - 2016-02-05 10:10 +0100
      Re: [PATCH] mm/slub: support left red zone Joonsoo Kim <js1304@gmail.com> - 2016-02-05 17:30 +0100
  Re: [PATCH] mm/slub: support left red zone Christoph Lameter <cl@linux.com> - 2016-02-05 10:00 +0100

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