linux-kernel - Re: [PATCH 20/34] xen: convert put_page() to put_user

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <746b2412-f48a-9722-2763-253a1b9c899d@nvidia.com>
Date:   Fri, 2 Aug 2019 12:25:01 -0700
From:   John Hubbard <jhubbard@...dia.com>
To:     "Weiny, Ira" <ira.weiny@...el.com>,
        Juergen Gross <jgross@...e.com>,
        "john.hubbard@...il.com" <john.hubbard@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>
CC:     "devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
        Dave Chinner <david@...morbit.com>,
        Christoph Hellwig <hch@...radead.org>,
        "Williams, Dan J" <dan.j.williams@...el.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "amd-gfx@...ts.freedesktop.org" <amd-gfx@...ts.freedesktop.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-rpi-kernel@...ts.infradead.org" 
        <linux-rpi-kernel@...ts.infradead.org>,
        "devel@...ts.orangefs.org" <devel@...ts.orangefs.org>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        "rds-devel@....oracle.com" <rds-devel@....oracle.com>,
        Jérôme Glisse <jglisse@...hat.com>,
        Jan Kara <jack@...e.cz>,
        "ceph-devel@...r.kernel.org" <ceph-devel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        "linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
        "linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
        "linux-xfs@...r.kernel.org" <linux-xfs@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "sparclinux@...r.kernel.org" <sparclinux@...r.kernel.org>,
        Jason Gunthorpe <jgg@...pe.ca>
Subject: Re: [PATCH 20/34] xen: convert put_page() to put_user_page*()

On 8/2/19 9:09 AM, Weiny, Ira wrote:
>>
>> On 02.08.19 07:48, John Hubbard wrote:
>>> On 8/1/19 9:36 PM, Juergen Gross wrote:
>>>> On 02.08.19 04:19, john.hubbard@...il.com wrote:
>>>>> From: John Hubbard <jhubbard@...dia.com>
>>> ...
>>> If that's not the case (both here, and in 3 or 4 other patches in this
>>> series, then as you said, I should add NULL checks to put_user_pages()
>>> and put_user_pages_dirty_lock().
>>
>> In this case it is not correct, but can easily be handled. The NULL case can
>> occur only in an error case with the pages array filled partially or not at all.
>>
>> I'd prefer something like the attached patch here.
> 
> I'm not an expert in this code and have not looked at it carefully but that patch does seem to be the better fix than forcing NULL checks on everyone.
> 

OK, I'll use Juergen's approach, and also check for that pattern in the
other patches.


thanks,
-- 
John Hubbard
NVIDIA