Re: [PATCH 0/2] mm,fork,security: introduce MADV_WIPEONFORK

From	Rik van Riel <riel@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 0/2] mm,fork,security: introduce MADV_WIPEONFORK
Date	2017-08-05 17:30 +0200
Message-ID	<ub9bA-6KA-7@gated-at.bofh.it> (permalink)
References	<uaQ8W-2CK-17@gated-at.bofh.it> <uaUvW-5hz-63@gated-at.bofh.it>
Organization	Red Hat, Inc

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On Sat, 2017-08-05 at 02:44 +0300, Kirill A. Shutemov wrote:
> On Fri, Aug 04, 2017 at 03:07:28PM -0400, riel@redhat.com wrote:
> > [resend because half the recipients got dropped due to IPv6
> > firewall issues]
> > 
> > Introduce MADV_WIPEONFORK semantics, which result in a VMA being
> > empty in the child process after fork. This differs from
> > MADV_DONTFORK
> > in one important way.
> > 
> > If a child process accesses memory that was MADV_WIPEONFORK, it
> > will get zeroes. The address ranges are still valid, they are just
> > empty.
> 
> I feel like we are repeating mistake we made with MADV_DONTNEED.
> 
> MADV_WIPEONFORK would require a specific action from kernel, ignoring
> the /advise/ would likely lead to application misbehaviour.
> 
> Is it something we really want to see from madvise()?

We already have various mandatory madvise behaviors in Linux,
including MADV_REMOVE, MADV_DONTFORK, and MADV_DONTDUMP.

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[PATCH 0/2] mm,fork,security: introduce MADV_WIPEONFORK riel@redhat.com - 2017-08-04 21:10 +0200
  Re: [PATCH 0/2] mm,fork,security: introduce MADV_WIPEONFORK "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-08-05 01:50 +0200
    Re: [PATCH 0/2] mm,fork,security: introduce MADV_WIPEONFORK Rik van Riel <riel@redhat.com> - 2017-08-05 17:30 +0200

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