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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