linux-kernel - Re: [PATCH] mm: mmap: Fix general protection fault in unlink_file

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Date:   Fri, 9 Oct 2020 06:39:04 +0000
From:   linmiaohe <linmiaohe@...wei.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
CC:     "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: mmap: Fix general protection fault in
 unlink_file_vma()

Andrew Morton <akpm@...ux-foundation.org> wrote:
> On Thu, 8 Oct 2020 07:17:18 +0000 linmiaohe <linmiaohe@...wei.com> wrote:
>
>> Andrew Morton <akpm@...ux-foundation.org> wrote:
>> > On Wed, 16 Sep 2020 05:07:33 -0400 Miaohe Lin <linmiaohe@...wei.com> wrote:
>> >
>> >> The syzbot reported the below general protection fault:
>>
>> >
>> >is this using the correct file?  I think it is, but please do check.
>> >
>> 
>> Many thanks for your reply.
>> 
>> Yes, I think so too. We do deny_write_access and mapping_map_writable on @file, so we should undo all of this on @file.
>> Since @file is unchanged over the second vma_merge() time, we'are using the correct @file to undo our temporary denial count.
>> 
>> But how should I check this explicitly ? I can't find out a way to do this. Could you please figure it out for me?
>
>I meant "please check (review) the code as it now is", not "please add a check" ;)
>

Oh, I see. I have reviewed the code carefully. The @file should be right one as I explained in previous email. ;)

Have a good day! ^_^