linux-kernel - RE: [PATCH v2] fs/proc: Optimize arrays defined by struct ctl

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <376fe4403af346ccbdc7294259b8d11a@AcuMS.aculab.com>
Date:   Thu, 24 Feb 2022 11:05:35 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Meng Tang' <tangmeng@...ontech.com>,
        "mcgrof@...nel.org" <mcgrof@...nel.org>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "yzaikin@...gle.com" <yzaikin@...gle.com>
CC:     "guoren@...nel.org" <guoren@...nel.org>,
        "nickhu@...estech.com" <nickhu@...estech.com>,
        "green.hu@...il.com" <green.hu@...il.com>,
        "deanbo422@...il.com" <deanbo422@...il.com>,
        "ebiggers@...nel.org" <ebiggers@...nel.org>,
        "tytso@....edu" <tytso@....edu>,
        "wad@...omium.org" <wad@...omium.org>,
        "john.johansen@...onical.com" <john.johansen@...onical.com>,
        "jmorris@...ei.org" <jmorris@...ei.org>,
        "serge@...lyn.com" <serge@...lyn.com>,
        "linux-csky@...r.kernel.org" <linux-csky@...r.kernel.org>,
        "linux-fscrypt@...r.kernel.org" <linux-fscrypt@...r.kernel.org>,
        "linux-security-module@...r.kernel.org" 
        <linux-security-module@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>
Subject: RE: [PATCH v2] fs/proc: Optimize arrays defined by struct ctl_path

From: Meng Tang <tangmeng@...ontech.com>
> Sent: 24 February 2022 10:53
> 
> Previously, arrays defined by struct ctl_path is terminated
> with an empty one. For example, when we actually only register
> one ctl_path, we've gone from 8 bytes to 16 bytes.
> 
...
> diff --git a/arch/csky/abiv1/alignment.c b/arch/csky/abiv1/alignment.c
> index 2df115d0e210..b9290a252d84 100644
> --- a/arch/csky/abiv1/alignment.c
> +++ b/arch/csky/abiv1/alignment.c
> @@ -340,14 +340,14 @@ static struct ctl_table sysctl_table[2] = {
>  	{}
>  };
> 
> -static struct ctl_path sysctl_path[2] = {
> -	{.procname = "csky"},
> -	{}
> +static struct ctl_path sysctl_path[1] = {
> +	{.procname = "csky"}
>  };
> +#define SYSCTL_PATH_NUM ARRAY_SIZE(sysctl_path)
> 
>  static int __init csky_alignment_init(void)
>  {
> -	 (sysctl_path, sysctl_table);
> +	register_sysctl_paths(sysctl_path, SYSCTL_PATH_NUM, sysctl_table);
>  	return 0;
>  }

That is horribly error prone.
What might work is to add the ctl_path_num parameter but leave in the
check for NULL.
Then add:

#define register_sysctl_paths(p, t) register_sysctl_paths(p, ARRAY_SIZE(t), t)

in the header file after the prototype.
Put the function name in () in the definition to stop the macro expansion.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)