linux-kernel - Re: [PATCH 02/20] exit: Remove calls of do

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Message-ID: <202110210858.41719190D2@keescook>
Date:   Thu, 21 Oct 2021 09:02:04 -0700
From:   Kees Cook <keescook@...omium.org>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Oleg Nesterov <oleg@...hat.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Jonas Bonn <jonas@...thpole.se>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        Stafford Horne <shorne@...il.com>,
        openrisc@...ts.librecores.org, Nick Hu <nickhu@...estech.com>,
        Greentime Hu <green.hu@...il.com>,
        Vincent Chen <deanbo422@...il.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        linux-s390@...r.kernel.org,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>, linux-sh@...r.kernel.org,
        linux-xtensa@...ux-xtensa.org, Chris Zankel <chris@...kel.net>,
        Max Filippov <jcmvbkbc@...il.com>
Subject: Re: [PATCH 02/20] exit: Remove calls of do_exit after noreturn
 versions of die

On Wed, Oct 20, 2021 at 12:43:48PM -0500, Eric W. Biederman wrote:
> On nds32, openrisc, s390, sh, and xtensa the function die never
> returns.  Mark die __noreturn so that no one expects die to return.
> Remove the do_exit calls after die as they will never be reached.

Maybe note that the "bust_spinlocks" calls are also redundant, since
they're in die(). I note that is a "mismatch" between the do_kill()
in die() (SIGSEGV) and after die() (SIGKILL). This patch makes no
behavioral change (the first caller would "win"), but I thought I'd note
it in case some architecture would prefer a different signal.

Reviewed-by: Kees Cook <keescook@...omium.org>

-Kees

-- 
Kees Cook