From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756420AbaDWOmk (ORCPT ); Wed, 23 Apr 2014 10:42:40 -0400 Received: from kanga.kvack.org ([205.233.56.17]:43432 "EHLO kanga.kvack.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752106AbaDWOmi (ORCPT ); Wed, 23 Apr 2014 10:42:38 -0400 Date: Wed, 23 Apr 2014 10:42:37 -0400 From: Benjamin LaHaise To: Matthew Wilcox Cc: Eric Biggers , viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] aio: Fix type of iterator variable in do_io_submit() Message-ID: <20140423144237.GY22552@kvack.org> References: <1398207423-21119-1-git-send-email-ebiggers3@gmail.com> <20140423141617.GE13050@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140423141617.GE13050@linux.intel.com> User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 23, 2014 at 10:16:17AM -0400, Matthew Wilcox wrote: > 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. Practically speaking, this change has no effect. The io_submit() syscall will exit far before we even hit INT_MAX because of the limits on the number of iocbs. -ben -- "Thought is the essence of where you are now."