linux-kernel - Re: [PATCH v5] printk: Userspace format enumeration support

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Message-ID: <YEnmUEscWfcmDE+5@kroah.com>
Date:   Thu, 11 Mar 2021 10:43:44 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Chris Down <chris@...isdown.name>, linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        John Ogness <john.ogness@...utronix.de>,
        Johannes Weiner <hannes@...xchg.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Kees Cook <keescook@...omium.org>, kernel-team@...com
Subject: Re: [PATCH v5] printk: Userspace format enumeration support

On Thu, Mar 11, 2021 at 10:34:46AM +0100, Petr Mladek wrote:
> On Wed 2021-03-10 13:16:43, Greg Kroah-Hartman wrote:
> > On Wed, Mar 10, 2021 at 12:12:57PM +0000, Chris Down wrote:
> > > Greg Kroah-Hartman writes:
> > > > On Wed, Mar 10, 2021 at 02:30:31AM +0000, Chris Down wrote:
> > > > > +	ps->file = debugfs_create_file(pi_get_module_name(mod), 0444, dfs_index,
> > > > > +				       ps, &dfs_index_fops);
> > > > > +
> > > > > +	if (IS_ERR(ps->file)) {
> > > > > +		pi_sec_remove(mod);
> > > > > +		return;
> > > > > +	}
> > > > 
> > > > No need to check this and try to clean up if there is a problem, just
> > > > save the pointer off and call debugfs_remove() when you want to clean
> > > > up.
> > > 
> > > Petr, what are your thoughts on this, since you requested the cleanup on
> > > debugfs failure? :-)
> > 
> > There is nothing to "clean up" if there is a debugfs failure here so I
> > don't see the need.
> 
> My main concern is that the allocated struct pi_sec must not be leaked
> when debugfs file was not created.
> 
> I still have to check if it would be freed even without the file
> when the module is going out.

To me it looks like it still will happen as pi_sec_remove() will be
called either way.

thanks,

greg k-h