linux-kernel - Re: [PATCH v7 9/9] sparc64: Add support for ADI (Application Data Integrity)

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Message-ID: <20170906223206.GA11481@amd>
Date:   Thu, 7 Sep 2017 00:32:06 +0200
From:   Pavel Machek <pavel@....cz>
To:     David Miller <davem@...emloft.net>
Cc:     khalid.aziz@...cle.com, dave.hansen@...ux.intel.com,
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Subject: Re: [PATCH v7 9/9] sparc64: Add support for ADI (Application Data
 Integrity)

On Tue 2017-09-05 14:44:56, David Miller wrote:
> From: Pavel Machek <pavel@....cz>
> Date: Mon, 4 Sep 2017 18:25:30 +0200
> 
> > Will gcc be able to compile code that uses these automatically? That
> > does not sound easy to me. Can libc automatically use this in malloc()
> > to prevent accessing freed data when buffers are overrun?
> > 
> > Is this for benefit of JITs?
> 
> Anything that can control mappings and the virtual address used to
> access memory can use ADI.
> 
> malloc() is of course one such case.  It can map memory with ADI
> enabled, and return buffer addresses to malloc() callers with the
> proper virtual address bits set to satisfy the ADI key checks.
> 
> And by induction anything using malloc() for it's memory allocation
> gets ADI protection as well.

I see; that's actually quite a nice trick.

I guess it does not protect against stack-based overflows, but should
help against heap-based overflows, so it improves security a bit, too.

Nice, thanks for explanation.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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