linux-kernel - Re: [PATCH RFC v2] slab: introduce kmalloc

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Date:	Tue, 14 Feb 2012 10:34:46 -0600 (CST)
From:	Christoph Lameter <cl@...ux.com>
To:	Xi Wang <xi.wang@...il.com>
cc:	Dan Carpenter <dan.carpenter@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jesper Juhl <jj@...osbits.net>, Jens Axboe <axboe@...nel.dk>,
	Pekka Enberg <penberg@...nel.org>,
	linux-kernel@...r.kernel.org, Matt Mackall <mpm@...enic.com>,
	David Rientjes <rientjes@...gle.com>
Subject: Re: [PATCH RFC v2] slab: introduce kmalloc_array

On Tue, 14 Feb 2012, Xi Wang wrote:

> On Feb 14, 2012, at 10:02 AM, Christoph Lameter wrote:
> > We could also catch these issues with BUG() or WARN_ON() and then return
> > zero.
>
> You cannot have SAFE_ARRAY_SIZE return 0 when an integer overflow
> occurs.

You can if you check the results later. A zero size return would be an
indication of an error. No need to pass it on to kmalloc.

> Besides, BUG() still allows DoS attacks and WARN_ON() would flood
> the log, especially if n is controlled from user space.  Neither
> seems appropriate here.

We have means at various level to control the "flood."

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