linux-kernel - Re: [patch] mfd: vexpress: use after free in vexpress_syscfg_regmap

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Message-ID: <20140611100752.GR5500@mwanda>
Date:	Wed, 11 Jun 2014 13:07:52 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Pawel Moll <pawel.moll@....com>
Cc:	Arnd Bergmann <arnd@...db.de>, Lee Jones <lee.jones@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>
Subject: Re: [patch] mfd: vexpress: use after free in
 vexpress_syscfg_regmap_init()

On Wed, Jun 11, 2014 at 10:22:22AM +0100, Pawel Moll wrote:
> On Wed, 2014-06-11 at 07:07 +0100, Dan Carpenter wrote:
> > We should return NULL if regmap_init() fails instead of continuing.
> > 
> > Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
> > 
> > diff --git a/drivers/misc/vexpress-syscfg.c b/drivers/misc/vexpress-syscfg.c
> > index 73068e5..2c0ddb2 100644
> > --- a/drivers/misc/vexpress-syscfg.c
> > +++ b/drivers/misc/vexpress-syscfg.c
> > @@ -231,10 +231,12 @@ static struct regmap *vexpress_syscfg_regmap_init(struct device *dev,
> >  	func->regmap = regmap_init(dev, NULL, func,
> >  			&vexpress_syscfg_regmap_config);
> >  
> > -	if (IS_ERR(func->regmap))
> > +	if (IS_ERR(func->regmap)) {
> >  		kfree(func);
> > -	else
> > -		list_add(&func->list, &syscfg->funcs);
> > +		return NULL;
> > +	}
> > +
> > +	list_add(&func->list, &syscfg->funcs);
> >  
> >  	return func->regmap;
> >  }
> 
> Not really, no. What made you think so?
> 
> vexpress_config_bridge_ops.regmap_init should return an ERR_PTR in case
> of troubles, not a NULL. See devm_regmap_init_vexpress_config() in
> drivers/bus/vexpress-config.c:
> 
>         regmap = bridge->ops->regmap_init(dev, bridge->context);
>         if (IS_ERR(regmap)) {

Ah...  That was sloppy of me.  There is a similar bug earlier and I'll
fix that as well.

regards,
dan carpenter

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