linux-kernel - Re: [PATCH] drivers: of: check input parameter name for __of_find

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Message-ID: <20150916001650.GA28082@linux-4gyl.site>
Date:	Wed, 16 Sep 2015 08:16:51 +0800
From:	Peng Fan <van.freenix@...il.com>
To:	Rob Herring <robh@...nel.org>
Cc:	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	Frank Rowand <frowand.list@...il.com>,
	Grant Likely <grant.likely@...aro.org>
Subject: Re: [PATCH] drivers: of: check input parameter name for
 __of_find_property

Hi Rob,

On Tue, Sep 15, 2015 at 10:56:28AM -0500, Rob Herring wrote:
> On 09/11/2015 08:44 AM, Peng Fan wrote:
> > Check input parameter 'name' for __of_find_property. If name is NULL,
> > of_prop_cmp->strcasecmp may trigger panic.
> 
> Arguably that could be a feature. Do you have a usecase where name being
> NULL is valid and panicking is a problem?

In drivers/pinctrl/devicetree.c

195                 propname = kasprintf(GFP_KERNEL, "pinctrl-%d", state);
196                 prop = of_find_property(np, propname, &size);
197                 kfree(propname);
198                 if (!prop)
199                         break;

If propname is NULL, of_find_property may trigger panic. Anyway propname should be checked
before passing to of_find_property.

I did not met panic message. I wrote this patch when I was reading the piece code.
I think the name parameter should be checked before doing string compare.

Regards,
Peng.

> 
> Rob
> 
> > 
> > Signed-off-by: Peng Fan <van.freenix@...il.com>
> > Cc: Rob Herring <robh+dt@...nel.org>
> > Cc: Frank Rowand <frowand.list@...il.com>
> > Cc: Grant Likely <grant.likely@...aro.org>
> > ---
> >  drivers/of/base.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/of/base.c b/drivers/of/base.c
> > index 8b5a187..e41436d 100644
> > --- a/drivers/of/base.c
> > +++ b/drivers/of/base.c
> > @@ -215,7 +215,7 @@ static struct property *__of_find_property(const struct device_node *np,
> >  {
> >  	struct property *pp;
> >  
> > -	if (!np)
> > +	if (!np || !name)
> >  		return NULL;
> >  
> >  	for (pp = np->properties; pp; pp = pp->next) {
> > 
> 
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