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Date: Tue, 27 Feb 2018 11:22:57 -0800
From: Laura Abbott <labbott@...hat.com>
To: P J P <ppandit@...hat.com>, kernel-hardening@...ts.openwall.com
Cc: Florian Weimer <fweimer@...hat.com>, P J P <pjp@...oraproject.org>
Subject: Re: [PATCH 1/1] Add an option to build kernel with -finit-local-vars
On 02/27/2018 03:15 AM, P J P wrote:
> From: P J P <pjp@...oraproject.org>
>
> Add a configuration option to build kernel with -finit-local-vars
> compiler option.[*] It'll zero initialize the automatic kernel
> function variables, thus helping to reduce kernel information
> leakage issues.
>
I think this would make the existing structleak plugin
(scripts/gcc-plugins/structleak_plugin.c) obsolete. This isn't
a bad thing but we'd need to figure out a deprecation strategy.
> [*] https://gcc.gnu.org/ml/gcc-patches/2014-06/msg00615.html
>
> Signed-off-by: P J P <pjp@...oraproject.org>
> ---
> Makefile | 4 ++++
> lib/Kconfig.debug | 8 ++++++++
> 2 files changed, 12 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index 659a7780aeb3..7b25a77470ca 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -781,6 +781,10 @@ KBUILD_CFLAGS += $(call cc-option, -femit-struct-debug-baseonly) \
> $(call cc-option,-fno-var-tracking)
> endif
>
> +ifdef CONFIG_FINIT_LOCAL_VARS
> +KBUILD_CFLAGS += $(call cc-option, -finit-local-vars)
> +endif
> +
> ifdef CONFIG_FUNCTION_TRACER
> ifndef CC_FLAGS_FTRACE
> CC_FLAGS_FTRACE := -pg
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 64155e310a9f..8da18d145c5b 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -206,6 +206,14 @@ config ENABLE_WARN_DEPRECATED
> Disable this to suppress the "warning: 'foo' is deprecated
> (declared at kernel/power/somefile.c:1234)" messages.
>
> +config FINIT_LOCAL_VARS
> + bool "Enable -finit-local-vars"
> + default n
> + help
> + Enable the -finit-local-vars compiler option during the kernel build.
> + It'll zero initialise the automatic kernel function variables, thus
> + helping to reduce kernel information leakage issues.
> +
A few words about the expected runtime/kernel size impact would be helpful.
Thanks,
Laura
> config ENABLE_MUST_CHECK
> bool "Enable __must_check logic"
> default y
>
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