From: Nathan Chancellor <nathan@kernel.org>
To: Will Deacon <will@kernel.org>, linux-kernel@vger.kernel.org
Cc: linux-security-module@vger.kernel.org,
Kees Cook <keescook@chromium.org>,
Nick Desaulniers <ndesaulniers@google.com>,
"Gustavo A . R . Silva" <gustavoars@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH] hardening: Default to INIT_STACK_ALL_ZERO if CC_HAS_AUTO_VAR_INIT_ZERO
Date: Tue, 14 Sep 2021 08:58:12 -0700 [thread overview]
Message-ID: <01f572ab-bea2-f246-2f77-2f119056db84@kernel.org> (raw)
In-Reply-To: <20210914102837.6172-1-will@kernel.org>
On 9/14/2021 3:28 AM, Will Deacon wrote:
> CC_HAS_AUTO_VAR_INIT_ZERO requires a supported set of compiler options
> distinct from those needed by CC_HAS_AUTO_VAR_INIT_PATTERN, Fix up
> the Kconfig dependency for INIT_STACK_ALL_ZERO to test for the former
> instead of the latter, as these are the options passed by the top-level
> Makefile.
>
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Nathan Chancellor <nathan@kernel.org>
> Cc: Nick Desaulniers <ndesaulniers@google.com>
> Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Fixes: dcb7c0b9461c ("hardening: Clarify Kconfig text for auto-var-init")
> Signed-off-by: Will Deacon <will@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
One comment below.
> ---
>
> I just noticed this while reading the code and I suspect it doesn't really
> matter in practice.
>
> security/Kconfig.hardening | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening
> index 90cbaff86e13..341e2fdcba94 100644
> --- a/security/Kconfig.hardening
> +++ b/security/Kconfig.hardening
> @@ -29,7 +29,7 @@ choice
> prompt "Initialize kernel stack variables at function entry"
> default GCC_PLUGIN_STRUCTLEAK_BYREF_ALL if COMPILE_TEST && GCC_PLUGINS
> default INIT_STACK_ALL_PATTERN if COMPILE_TEST && CC_HAS_AUTO_VAR_INIT_PATTERN
> - default INIT_STACK_ALL_ZERO if CC_HAS_AUTO_VAR_INIT_PATTERN
> + default INIT_STACK_ALL_ZERO if CC_HAS_AUTO_VAR_INIT_ZERO
> default INIT_STACK_NONE
> help
> This option enables initialization of stack variables at
>
While I think this change is correct in and of itself,
CONFIG_INIT_STACK_ALL_ZERO is broken with GCC 12.x, as
CONFIG_CC_HAS_AUTO_VAR_INIT_ZERO won't be set even though GCC now
supports -ftrivial-auto-var-init=zero because GCC does not implement the
-enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang
flag for obvious reasons ;) the cc-option call probably needs to be
adjusted.
Cheers,
Nathan
next prev parent reply other threads:[~2021-09-14 15:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-14 10:28 [PATCH] hardening: Default to INIT_STACK_ALL_ZERO if CC_HAS_AUTO_VAR_INIT_ZERO Will Deacon
2021-09-14 15:58 ` Nathan Chancellor [this message]
2021-09-14 17:21 ` Kees Cook
2021-09-14 18:53 ` Nick Desaulniers
2021-09-14 19:09 ` Kees Cook
2021-09-14 19:14 ` Kees Cook
2021-09-14 19:22 ` Nick Desaulniers
2021-09-14 19:36 ` Nathan Chancellor
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=01f572ab-bea2-f246-2f77-2f119056db84@kernel.org \
--to=nathan@kernel.org \
--cc=gregkh@linuxfoundation.org \
--cc=gustavoars@kernel.org \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=ndesaulniers@google.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).