linux-kernel - Re: [PATCH] aio: Fix type of iterator variable in do_io

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Date:	Wed, 23 Apr 2014 10:16:17 -0400
From:	Matthew Wilcox <willy@...ux.intel.com>
To:	Eric Biggers <ebiggers3@...il.com>
Cc:	viro@...iv.linux.org.uk, bcrl@...ck.org,
	linux-fsdevel@...r.kernel.org, linux-aio@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] aio: Fix type of iterator variable in do_io_submit()

On Tue, Apr 22, 2014 at 05:57:03PM -0500, Eric Biggers wrote:
> do_io_submit() iterated over the userspace iocb structure pointers using
> a variable i of type 'int'.  This was wrong since 'nr', the number of
> iocb structure pointers, could potentially be up to LONG_MAX /
> sizeof(struct iocb *).  Fix it (and also remove the unnecessary
> initialization to 0).

You're not wrong, but do we *really* want users to be able to submit
144115188075855872 I/Os with a single system call?  How about limiting
them to a single billion?  Given that they have to allocate 64GB of
*control* data structures to submit this many I/Os, I think this will
be sufficient for many years to come.
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