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Message-ID: <1555078584.26196.50.camel@lca.pw>
Date: Fri, 12 Apr 2019 10:16:24 -0400
From: Qian Cai <cai@....pw>
To: Alexander Potapenko <glider@...gle.com>, akpm@...ux-foundation.org
Cc: linux-security-module@...r.kernel.org, linux-mm@...ck.org,
ndesaulniers@...gle.com, kcc@...gle.com, dvyukov@...gle.com,
keescook@...omium.org, sspatil@...roid.com, labbott@...hat.com,
kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH] mm: security: introduce CONFIG_INIT_HEAP_ALL
On Fri, 2019-04-12 at 14:45 +0200, Alexander Potapenko wrote:
> This config option adds the possibility to initialize newly allocated
> pages and heap objects with zeroes. This is needed to prevent possible
> information leaks and make the control-flow bugs that depend on
> uninitialized values more deterministic.
>
> Initialization is done at allocation time at the places where checks for
> __GFP_ZERO are performed. We don't initialize slab caches with
> constructors or SLAB_TYPESAFE_BY_RCU to preserve their semantics.
>
> For kernel testing purposes filling allocations with a nonzero pattern
> would be more suitable, but may require platform-specific code. To have
> a simple baseline we've decided to start with zero-initialization.
>
> No performance optimizations are done at the moment to reduce double
> initialization of memory regions.
Sounds like this has already existed in some degree, i.e.,
CONFIG_PAGE_POISONING_ZERO
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