linux-kernel - Re: [PATCH] backlight: check null deference of name when device is registered

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Message-id: <004301cded41$06e0b7e0$14a227a0$%han@samsung.com>
Date:	Tue, 08 Jan 2013 10:39:40 +0900
From:	Jingoo Han <jg1.han@...sung.com>
To:	'Andrew Morton' <akpm@...ux-foundation.org>
Cc:	'LKML' <linux-kernel@...r.kernel.org>, linux-fbdev@...r.kernel.org,
	'Richard Purdie' <rpurdie@...ys.net>,
	'Devendra Naga' <devendra.aaru@...il.com>,
	'Jingoo Han' <jg1.han@...sung.com>
Subject: Re: [PATCH] backlight: check null deference of name when device is
 registered

On Tuesday, January 08, 2013 10:36 AM, Andrew Morton wrote
> On Tue, 08 Jan 2013 10:25:35 +0900 Jingoo Han <jg1.han@...sung.com> wrote:
> 
> > On Tuesday, January 08, 2013 9:02 AM, Andrew Morton wrote
> > > On Fri, 04 Jan 2013 17:29:11 +0900
> > > Jingoo Han <jg1.han@...sung.com> wrote:
> > >
> > > > NULL deference of name is checked when device is registered.
> > > > If the name is null, it will cause a kernel oops in dev_set_name().
> > > >
> > > > ...
> > > >
> > > > --- a/drivers/video/backlight/backlight.c
> > > > +++ b/drivers/video/backlight/backlight.c
> > > > @@ -292,6 +292,11 @@ struct backlight_device *backlight_device_register(const char *name,
> > > >  	struct backlight_device *new_bd;
> > > >  	int rc;
> > > >
> > > > +	if (name == NULL) {
> > > > +		pr_err("backlight name is null\n");
> > > > +		return ERR_PTR(-EINVAL);
> > > > +	}
> > > > +
> > > >  	pr_debug("backlight_device_register: name=%s\n", name);
> > >
> > > I don't understand this.
> > >
> > > Is there some driver which is calling these functions with name=NULL?
> > > If so, which one(s)?
> >
> > No, there is no one.
> >
> > >
> > > If "no" then why don't we declare that "passing name=NULL is a bug" and
> > > leave the code as-is?
> >
> > Do you mean following?
> >
> > +	if (name == NULL)
> > +		pr_err("passing name=NULL is a bug");
> > +
> >   	pr_debug("backlight_device_register: name=%s\n", name);
> 
> Nope; I'm suggesting we leave the code alone.  If someone passes in
> NULL they will get a nice oops and their bug will then get fixed.

I see. I agree with you.
Please, abandon this patch.

Best regards,
Jingoo Han

> 
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