linux-kernel - Re: [PATCH] drivers: acpi: fan.c move a dereference below the NULL test

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Date:	Mon, 22 Feb 2010 09:37:03 +0800
From:	Zhang Rui <rui.zhang@...el.com>
To:	Len Brown <lenb@...nel.org>
Cc:	Darren Jenkins <darrenrjenkins@...il.com>,
	Thomas Renninger <trenn@...e.de>,
	Alexey Dobriyan <adobriyan@...il.com>,
	Matthew Garrett <mjg@...hat.com>,
	linux ACPI <linux-acpi@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Kernel Janitors <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH] drivers: acpi: fan.c move a dereference below the NULL
 test

On Fri, 2010-02-19 at 13:27 +0800, Len Brown wrote:
> I think think this is a run-time check for a programming error,
> and the current fashion is to delete the check and take a fault
> if this happens so the caller can be fixed.
> 
I agree.

> There are a couple of checks like this in fan.c --
> perhaps Rui can clean them up when he comes back next week.
> 
I'll send the cleanup patch later.

thanks,
rui

> thanks,
> Len Brown, Intel Open Source Technology Center
> 
> On Thu, 11 Feb 2010, Darren Jenkins wrote:
> 
> > In acpi_fan_remove() device is being dereferenced before the NULL test.
> > This reorders the code to ensure it is checked for NULL first.
> > 
> > Coverity CID: 2758
> > 
> > Signed-off-by: Darren Jenkins <darrenrjenkins@...il.com>
> > ---
> >  drivers/acpi/fan.c |    9 +++++++--
> >  1 files changed, 7 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/acpi/fan.c b/drivers/acpi/fan.c
> > index acf2ab2..dc39640 100644
> > --- a/drivers/acpi/fan.c
> > +++ b/drivers/acpi/fan.c
> > @@ -298,9 +298,14 @@ static int acpi_fan_add(struct acpi_device *device)
> >  
> >  static int acpi_fan_remove(struct acpi_device *device, int type)
> >  {
> > -	struct thermal_cooling_device *cdev = acpi_driver_data(device);
> > +	struct thermal_cooling_device *cdev;
> > +
> > +	if (!device)
> > +		return -EINVAL;
> > +
> > +	cdev = acpi_driver_data(device);
> >  
> > -	if (!device || !cdev)
> > +	if (!cdev)
> >  		return -EINVAL;
> >  
> >  	acpi_fan_remove_fs(device);
> > -- 
> > 1.6.3.3
> > 
> > 
> > 
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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> > 


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