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Date:   Tue, 5 Dec 2023 23:41:32 +0100
From:   Thomas =?utf-8?Q?Wei=C3=9Fschuh?= <linux@weissschuh.net>
To:     Luis Chamberlain <mcgrof@kernel.org>
Cc:     Kees Cook <keescook@chromium.org>,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Iurii Zaikin <yzaikin@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Joel Granados <j.granados@samsung.com>,
        linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v2 13/18] sysctl: move sysctl type to ctl_table_header
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References: <20231204-const-sysctl-v2-0-7a5060b11447@weissschuh.net>
 <20231204-const-sysctl-v2-13-7a5060b11447@weissschuh.net>
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On 2023-12-05 14:33:38-0800, Luis Chamberlain wrote:
> On Mon, Dec 04, 2023 at 08:52:26AM +0100, Thomas Weißschuh wrote:
> > @@ -231,7 +231,8 @@ static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
> >  		return -EROFS;
> >  
> >  	/* Am I creating a permanently empty directory? */
> > -	if (sysctl_is_perm_empty_ctl_header(header)) {
> > +	if (header->ctl_table == sysctl_mount_point ||
> > +	    sysctl_is_perm_empty_ctl_header(header)) {
> >  		if (!RB_EMPTY_ROOT(&dir->root))
> >  			return -EINVAL;
> >  		sysctl_set_perm_empty_ctl_header(dir_h);
> 
> While you're at it.

This hunk is completely gone in v3/the code that you merged.

> This just made me cringe, and curious if some other changes
> could be done to make this obviously clear during patch review
> that this is safe.

Which kind of unsafety do you envision here?