From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753357AbcHUVPb (ORCPT ); Sun, 21 Aug 2016 17:15:31 -0400 Received: from mail-pa0-f66.google.com ([209.85.220.66]:36525 "EHLO mail-pa0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752602AbcHUVP3 (ORCPT ); Sun, 21 Aug 2016 17:15:29 -0400 Subject: Re: [PATCH 4/8] pipe: fix limit checking in pipe_set_size() To: Vegard Nossum , Andrew Morton References: <67ce15aa-cf43-0c89-d079-2d966177c56d@gmail.com> <7f0732a9-6172-e92d-7c5b-473b769fe37e@gmail.com> <57B6C3B7.2000903@oracle.com> Cc: mtk.manpages@gmail.com, Willy Tarreau , socketpair@gmail.com, Tetsuo Handa , Jens Axboe , Al Viro , linux-api@vger.kernel.org, linux-kernel@vger.kernel.org From: "Michael Kerrisk (man-pages)" Message-ID: <8b893c3b-aa41-ffb3-a652-a42a746d26fb@gmail.com> Date: Mon, 22 Aug 2016 09:14:27 +1200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/21/2016 10:33 PM, Vegard Nossum wrote: > On 08/20/2016 01:17 AM, Michael Kerrisk (man-pages) wrote: >> On 08/20/2016 08:56 AM, Michael Kerrisk (man-pages) wrote: >>> On 08/19/2016 08:30 PM, Vegard Nossum wrote: >>>> Is there any reason why we couldn't do the (size > pipe_max_size) check >>>> before calling account_pipe_buffers()? >>> >>> No reason that I can see. Just a little more work to be done in the >>> code, I think. >> >> And, just so I make sure we're understanding each other... I assume you >> mean changing the code here to something like: > [...] >> if (nr_pages > pipe->buffers && >> size > pipe_max_size && !capable(CAP_SYS_RESOURCE)) >> return -EPERM; >> >> user_bufs = account_pipe_buffers(pipe->user, pipe->buffers, nr_pages); >> >> if (nr_pages > pipe->buffers && >> too_many_pipe_buffers_hard(user_bufs || >> too_many_pipe_buffers_soft(user_bufs)) && >> !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) { >> ret = -EPERM; >> goto out_revert_acct; >> } >> >> Right? > > Yup, that's what I had in mind. Okay -- changed. > (The parantheses are messed up though.) Yup, was just a quick untested edit to make sure we meant the same thing. Thanks, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/