linux-kernel - Re: [PATCH 1/3] arch/powerpc: Add kmalloc NULL tests

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Message-ID: <Pine.LNX.4.64.0908070850380.20445@pc-004.diku.dk>
Date:	Fri, 7 Aug 2009 08:51:08 +0200 (CEST)
From:	Julia Lawall <julia@...u.dk>
To:	"Daniel K." <dk@...no>
Cc:	benh@...nel.crashing.org, paulus@...ba.org,
	linuxppc-dev@...abs.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 1/3] arch/powerpc: Add kmalloc NULL tests

On Fri, 7 Aug 2009, Daniel K. wrote:

> Julia Lawall wrote:
> > --- a/arch/powerpc/sysdev/fsl_rio.c
> > +++ b/arch/powerpc/sysdev/fsl_rio.c
> > @@ -1057,6 +1057,10 @@ int fsl_rio_setup(struct of_device *dev)
> >     law_start, law_size);
> >  
> > 	ops = kmalloc(sizeof(struct rio_ops), GFP_KERNEL);
> > +	if (!ops) {
> > +		rc = -ENOMEM;
> > +		goto err_ops;
> > +	}
> >   ops->lcread = fsl_local_config_read;
> >   ops->lcwrite = fsl_local_config_write;
> >   ops->cread = fsl_rio_config_read;
> > @@ -1064,6 +1068,10 @@ int fsl_rio_setup(struct of_device *dev)
> >   ops->dsend = fsl_rio_doorbell_send;
> >  
> > 	port = kzalloc(sizeof(struct rio_mport), GFP_KERNEL);
> > +	if (!port) {
> > +		rc = -ENOMEM;
> > +		goto err_port;
> > +	}
> >   port->id = 0;
> >   port->index = 0;
> >  
> > @@ -1071,7 +1079,7 @@ int fsl_rio_setup(struct of_device *dev)
> >   if (!priv) {
> >    printk(KERN_ERR "Can't alloc memory for 'priv'\n");
> >    rc = -ENOMEM;
> > -		goto err;
> > +		goto err_priv;
> >   }
> >  
> >   INIT_LIST_HEAD(&port->dbells);
> > @@ -1169,13 +1177,15 @@ int fsl_rio_setup(struct of_device *dev)
> >  
> >  	return 0;
> > err:
> > -	if (priv)
> > -		iounmap(priv->regs_win);
> > -	kfree(ops);
> > +	iounmap(priv->regs_win);
> > +err_priv:
> > 	kfree(priv);
> > +err_port:
> > 	kfree(port);
> > +err_ops:
> > +	kfree(ops);
> >   return rc;
> 
> There seems to be a goto-off-by-one error here.
> 
> If xxxx = kxalloc() fails, you goto err_xxxx, and do a kfree(xxxx) where xxxx
> is
> already proven to be NULL.
> 
> Is there a reason for this that eludes me?

No, I messed up...  I will fix it.

julia


> I'd expect that last hunk to look something like
> 
> @@ -1169,13 +1177,15 @@ int fsl_rio_setup(struct of_device *dev)
> 
> 	return 0;
> err:
> -	if (priv)
> -		iounmap(priv->regs_win);
> -	kfree(ops);
> +	iounmap(priv->regs_win);
> 	kfree(priv);
> +err_priv:
> 	kfree(port);
> +err_port:
> +	kfree(ops);
> +err_ops:
> 	return rc;
> }
> 
> 
> Daniel K.
> --
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