linux-kernel - Re: [PATCH] mfd: fix unintentional NULL check in menelaus_set

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Message-ID: <20140528161839.GA16693@lianli>
Date:	Wed, 28 May 2014 18:18:39 +0200
From:	Emil Goode <emilgoode@...il.com>
To:	Lee Jones <lee.jones@...aro.org>
Cc:	Samuel Ortiz <sameo@...ux.intel.com>,
	Jingoo Han <jg1.han@...sung.com>, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] mfd: fix unintentional NULL check in
 menelaus_set_voltage()

Hello,

On Wed, May 28, 2014 at 04:20:11PM +0100, Lee Jones wrote:
> On Wed, 28 May 2014, Emil Goode wrote:
> 
> > The struct menelaus_vtg pointer vtg cannot be NULL here
> > so the condition is never true and if it ever was true
> > it would lead to a NULL pointer dereference when we goto
> > label set_voltage.
> > 
> > Before the below patch was applied the code was:
> > 
> > if (vtg == 0)
> > 
> > The intention was to check if vtg_val is 0.
> > 
> > commit 59a9f7a32adf6537b4e4db8ca204eeb77d7a634e
> > ("mfd: menelaus: Use NULL instead of 0")
> > 
> > Signed-off-by: Emil Goode <emilgoode@...il.com>
> > ---
> > Hello,
> > 
> > This is only build tested, it would be good to get a comment
> > from someone who is familiar with this code.
> > 
> > Found using coccinelle.
> > 
> > Best regards,
> > 
> > Emil Goode
> > 
> >  drivers/mfd/menelaus.c |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/mfd/menelaus.c b/drivers/mfd/menelaus.c
> > index ad25bfa..4859597 100644
> > --- a/drivers/mfd/menelaus.c
> > +++ b/drivers/mfd/menelaus.c
> > @@ -466,7 +466,7 @@ static int menelaus_set_voltage(const struct menelaus_vtg *vtg, int mV,
> >  	struct i2c_client *c = the_menelaus->client;
> >  
> >  	mutex_lock(&the_menelaus->lock);
> > -	if (!vtg)
> > +	if (vtg_val == 0)
> 
> I would prefer:
> 
>   if (!vtg_val)

Ok, I will resend.

Best regards,

Emil Goode
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