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Date: Tue, 9 Apr 2019 10:29:30 +0200
From: Alexander Potapenko <glider@...gle.com>
To: Randy Dunlap <rdunlap@...radead.org>
Cc: Masahiro Yamada <yamada.masahiro@...ionext.com>, James Morris <jmorris@...ei.org>, 
	"Serge E. Hallyn" <serge@...lyn.com>, 
	linux-security-module <linux-security-module@...r.kernel.org>, 
	Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>, Nick Desaulniers <ndesaulniers@...gle.com>, 
	Kostya Serebryany <kcc@...gle.com>, Dmitriy Vyukov <dvyukov@...gle.com>, Kees Cook <keescook@...omium.org>, 
	Sandeep Patil <sspatil@...roid.com>, 
	Kernel Hardening <kernel-hardening@...ts.openwall.com>
Subject: Re: [PATCH v3 1/2] initmem: introduce CONFIG_INIT_ALL_MEMORY and CONFIG_INIT_ALL_STACK

On Tue, Apr 9, 2019 at 12:15 AM Randy Dunlap <rdunlap@...radead.org> wrote:
>
> On 4/8/19 10:04 AM, Alexander Potapenko wrote:
> > diff --git a/security/Kconfig.initmem b/security/Kconfig.initmem
> > new file mode 100644
> > index 000000000000..5e49a55382ad
> > --- /dev/null
> > +++ b/security/Kconfig.initmem
> > @@ -0,0 +1,29 @@
> > +menu "Initialize all memory"
> > +
> > +config CC_HAS_AUTO_VAR_INIT
> > +     def_bool $(cc-option,-ftrivial-auto-var-init=pattern)
> > +
> > +config INIT_ALL_MEMORY
> > +     bool "Initialize all memory"
> > +     default n
> > +     help
> > +       Enforce memory initialization to mitigate infoleaks and make
> > +       the control-flow bugs depending on uninitialized values more
> > +       deterministic.
> > +
> > +if INIT_ALL_MEMORY
> > +
> > +config INIT_ALL_STACK
> > +     bool "Initialize all stack"
> > +     depends on INIT_ALL_MEMORY
>
> This "depends on" is redundant with the "if INIT_ALL_MEMORY" above it.
Ack, thank you!
> Similar comment for patch 2/2 and INIT_ALL_HEAP.
>
> > +     depends on CC_HAS_AUTO_VAR_INIT || (HAVE_GCC_PLUGINS && PLUGIN_HOSTCC != "")
> > +     select GCC_PLUGINS if !CC_HAS_AUTO_VAR_INIT
> > +     select GCC_PLUGIN_STRUCTLEAK if !CC_HAS_AUTO_VAR_INIT
> > +     select GCC_PLUGIN_STRUCTLEAK_BYREF_ALL if !CC_HAS_AUTO_VAR_INIT
> > +     default y
> > +     help
> > +       Initialize uninitialized stack data with a fixed pattern
> > +       (0x00 in GCC, 0xAA in Clang).
> > +
> > +endif # INIT_ALL_MEMORY
> > +endmenu
>
>
> --
> ~Randy



-- 
Alexander Potapenko
Software Engineer

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