linux-kernel - Re: [PATCH] pinctrl: devicetree: fix refcount leak in pinctrl_dt_to

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Message-ID: <d80e09d8-5f35-4865-9fe8-195b86527972@moroto.mountain>
Date: Wed, 17 Apr 2024 18:38:46 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Andy Shevchenko <andriy.shevchenko@...el.com>
Cc: Zeng Heng <zengheng4@...wei.com>, linus.walleij@...aro.org,
	linux-kernel@...r.kernel.org, xiexiuqi@...wei.com,
	linux-gpio@...r.kernel.org, weiyongjun1@...wei.com,
	liwei391@...wei.com
Subject: Re: [PATCH] pinctrl: devicetree: fix refcount leak in
 pinctrl_dt_to_map()

On Wed, Apr 17, 2024 at 06:30:59PM +0300, Andy Shevchenko wrote:
> On Mon, Apr 15, 2024 at 06:53:28PM +0800, Zeng Heng wrote:
> > If we fail to allocate propname buffer, we need to drop the reference
> > count we just took. Because the pinctrl_dt_free_maps() includes the
> > droping operation, here we call it directly.
> 
> ...
> 
> >  	for (state = 0; ; state++) {
> >  		/* Retrieve the pinctrl-* property */
> >  		propname = kasprintf(GFP_KERNEL, "pinctrl-%d", state);
> > -		if (!propname)
> > -			return -ENOMEM;
> > +		if (!propname) {
> > +			ret = -ENOMEM;
> > +			goto err;
> > +		}
> >  		prop = of_find_property(np, propname, &size);
> >  		kfree(propname);
> >  		if (!prop) {
> >  			if (state == 0) {
> > -				of_node_put(np);
> > -				return -ENODEV;
> > +				ret = -ENODEV;
> > +				goto err;
> 
> Has it been tested? How on earth is this a correct change?
> 
> We iterate over state numbers until we have properties available. This chunk is
> _successful_ exit path, we may not free parsed maps! Am I wrong?

In this path state == 0 so we haven't had a successful iteration yet.

regards,
dan carpenter