linux-kernel - Re: [PATCH 10/10] mm: Prevent munmap and remap_file

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Message-ID: <1528402501.5265.23.camel@2b52.sc.intel.com>
Date:   Thu, 07 Jun 2018 13:15:01 -0700
From:   Yu-cheng Yu <yu-cheng.yu@...el.com>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>, linux-doc@...r.kernel.org,
        Linux-MM <linux-mm@...ck.org>,
        linux-arch <linux-arch@...r.kernel.org>, X86 ML <x86@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. J. Lu" <hjl.tools@...il.com>,
        "Shanbhogue, Vedvyas" <vedvyas.shanbhogue@...el.com>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Jonathan Corbet <corbet@....net>,
        Oleg Nesterov <oleg@...hat.com>, Arnd Bergmann <arnd@...db.de>,
        mike.kravetz@...cle.com
Subject: Re: [PATCH 10/10] mm: Prevent munmap and remap_file_pages of shadow
 stack

On Thu, 2018-06-07 at 11:50 -0700, Andy Lutomirski wrote:
> On Thu, Jun 7, 2018 at 7:41 AM Yu-cheng Yu <yu-cheng.yu@...el.com> wrote:
> 
> blocking remap_file_pages() seems reasonable.  I'm not sure what's
> wrong with munmap().

Yes, maybe we don't need to block munmap().  If the shadow stack is
unmapped, the application gets a fault.  I will remove the patch.