linux-kernel - Re: [PATCH 8/8] sysctl: Warn on an empty procname element

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Date: Fri, 14 Jun 2024 15:01:10 +0200
From: Joel Granados <j.granados@...sung.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
	Will Deacon <will@...nel.org>, Waiman Long <longman@...hat.com>, Boqun Feng
	<boqun.feng@...il.com>, Suren Baghdasaryan <surenb@...gle.com>, "Kent
 Overstreet" <kent.overstreet@...ux.dev>, Andrew Morton
	<akpm@...ux-foundation.org>, Luis Chamberlain <mcgrof@...nel.org>, Kees Cook
	<keescook@...omium.org>, "David S. Miller" <davem@...emloft.net>, "Eric
 Dumazet" <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo
	Abeni <pabeni@...hat.com>, <linux-kernel@...r.kernel.org>,
	<linux-mm@...ck.org>, <linux-fsdevel@...r.kernel.org>,
	<netdev@...r.kernel.org>
Subject: Re: [PATCH 8/8] sysctl: Warn on an empty procname element

On Tue, Jun 04, 2024 at 08:29:26AM +0200, Joel Granados via B4 Relay wrote:
> From: Joel Granados <j.granados@...sung.com>
> 
> Add a pr_err warning in case a ctl_table is registered with a sentinel
> element containing a NULL procname.
> 
> Signed-off-by: Joel Granados <j.granados@...sung.com>
> ---
>  fs/proc/proc_sysctl.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
> index 806700b70dea..f65098de5fcb 100644
> --- a/fs/proc/proc_sysctl.c
> +++ b/fs/proc/proc_sysctl.c
> @@ -1119,6 +1119,8 @@ static int sysctl_check_table(const char *path, struct ctl_table_header *header)
>  	struct ctl_table *entry;
>  	int err = 0;
>  	list_for_each_table_entry(entry, header) {
> +		if (!entry->procname)
> +			err |= sysctl_err(path, entry, "procname is null");
>  		if ((entry->proc_handler == proc_dostring) ||
>  		    (entry->proc_handler == proc_dobool) ||
>  		    (entry->proc_handler == proc_dointvec) ||
> 
> -- 
> 2.43.0
> 
> 
To add to this check, I sent out a static analysis check to smatch in
such a way that a warning will be printed out if there is a ctl_table
element with a procname or prog_handler that are NULL. You can see it
here https://lore.kernel.org/all/20240614-master-v1-1-c652f5aa15fb@samsung.com/

Best
-- 

Joel Granados