Date: Tue, 14 Feb 2012 10:34:46 -0600 (CST)
From: Christoph Lameter <cl@linux.com>
To: Xi Wang <xi.wang@gmail.com>
cc: Dan Carpenter <dan.carpenter@oracle.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Jesper Juhl <jj@chaosbits.net>, Jens Axboe <axboe@kernel.dk>,
        Pekka Enberg <penberg@kernel.org>, linux-kernel@vger.kernel.org,
        Matt Mackall <mpm@selenic.com>, David Rientjes <rientjes@google.com>
Subject: Re: [PATCH RFC v2] slab: introduce kmalloc_array
In-Reply-To: <8F83835C-366C-46AC-A50A-3F680B7D2D83@gmail.com>
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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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