linux-kernel - Re: [PATCH v2] [RFC] security: allow using Clang's zero initialization for stack variables

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Message-ID: <CANP3RGcvZ-TBoTo2MeCbF=TWoY2sGv21TQ5btJoh+952rscLKg@mail.gmail.com>
Date:   Tue, 16 Jun 2020 05:20:54 -0700
From:   Maciej Żenczykowski <maze@...gle.com>
To:     Alexander Potapenko <glider@...gle.com>
Cc:     Greg KH <gregkh@...uxfoundation.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Kees Cook <keescook@...omium.org>,
        James Morris <jmorris@...ei.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-security-module <linux-security-module@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] [RFC] security: allow using Clang's zero
 initialization for stack variables

> We could make INIT_STACK_ALL_ZERO fall back to INIT_STACK_ALL_PATTERN
> if the compiler flag goes away - does this make sense?

No, I'm pretty sure failing to build, or at least not setting anything
is better.
AFAIK pattern actually introduces new bugs that aren't visible at all
with neither of these flags set.
(because in practice the default no flag behaviour seems to zero some
stuff [probably padding] that it doesn't with pattern)