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

[Pavel Machek <pavel@ucw.cz>]

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On Tue 2017-09-05 14:44:56, David Miller wrote:
> From: Pavel Machek <pavel@ucw.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
-- 
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