linux-kernel - Re: [PATCH 08/11] sysctl: Add size to register_sysctl

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 21 Jun 2023 13:36:46 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Joel Granados <j.granados@...sung.com>
Cc:     mcgrof@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        Theodore Ts'o <tytso@....edu>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Juergen Gross <jgross@...e.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Benjamin LaHaise <bcrl@...ck.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>,
        Jeff Layton <jlayton@...nel.org>,
        Chuck Lever <chuck.lever@...cle.com>, Jan Kara <jack@...e.cz>,
        Kees Cook <keescook@...omium.org>,
        Iurii Zaikin <yzaikin@...gle.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Balbir Singh <bsingharora@...il.com>,
        Eric Biederman <ebiederm@...ssion.com>,
        "Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
        Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Will Deacon <will@...nel.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Muchun Song <muchun.song@...ux.dev>,
        Naoya Horiguchi <naoya.horiguchi@....com>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        David Howells <dhowells@...hat.com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Paul Moore <paul@...l-moore.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
        Amir Goldstein <amir73il@...il.com>,
        John Fastabend <john.fastabend@...il.com>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>, Yonghong Song <yhs@...com>,
        KP Singh <kpsingh@...nel.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
        Waiman Long <longman@...hat.com>,
        Boqun Feng <boqun.feng@...il.com>,
        John Ogness <john.ogness@...utronix.de>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Valentin Schneider <vschneid@...hat.com>,
        Andy Lutomirski <luto@...capital.net>,
        Will Drewry <wad@...omium.org>,
        Mark Rutland <mark.rutland@....com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org,
        linux-aio@...ck.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org, bpf@...r.kernel.org, kexec@...ts.infradead.org,
        linux-trace-kernel@...r.kernel.org, keyrings@...r.kernel.org,
        linux-security-module@...r.kernel.org
Subject: Re: [PATCH 08/11] sysctl: Add size to register_sysctl_init

On Wed 2023-06-21 11:09:57, Joel Granados wrote:
> In order to remove the end element from the ctl_table struct arrays, we
> explicitly define the size when registering the targes. We add a size
> argument to the register_sysctl_init call and pass an ARRAY_SIZE for all
> the callers.

This does not explain the motivatin why the end element is removed.

I agree with Jiri that saving 9k is a questionable gain. According to
the cover letter it saved 0,00%. It is because it saved 9k with allyes
config which produces huge kernel. IMHO, the 9k might be interesting
only for a tiny kernel. But I guess that it would safe much less
bytes there.

And the code with the added ARRAY_SIZE() parameter looks worse than before.

> diff --git a/kernel/printk/sysctl.c b/kernel/printk/sysctl.c
> index c228343eeb97..28f37b86414e 100644
> --- a/kernel/printk/sysctl.c
> +++ b/kernel/printk/sysctl.c
> @@ -81,5 +81,6 @@ static struct ctl_table printk_sysctls[] = {
>  
>  void __init printk_sysctl_init(void)
>  {
> -	register_sysctl_init("kernel", printk_sysctls);
> +	register_sysctl_init("kernel", printk_sysctls,
> +			     ARRAY_SIZE(printk_sysctls));
>  }

Is register_sysctl_init() still ready to handle the last empty element,
please? I am not in Cc on the related patches.

Best Regards,
Petr