linux-kernel - Re: [PATCH] staging: unisys: virtpci: virtpci.c: Fix for possible null pointer dereference

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Message-ID: <20141214224123.GA4288@kroah.com>
Date:	Sun, 14 Dec 2014 14:41:23 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
Cc:	Benjamin Romer <benjamin.romer@...sys.com>,
	David Kershner <david.kershner@...sys.com>,
	Ken Cox <jkc@...hat.com>,
	Erik Arfvidson <erik.arfvidson@...sys.com>,
	Silvio F <silvio.fricke@...il.com>, sparmaintainer@...sys.com,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: unisys: virtpci: virtpci.c:  Fix for possible
 null pointer dereference

On Sun, Dec 14, 2014 at 11:41:11PM +0100, Rickard Strandqvist wrote:
> There is otherwise a risk of a possible null pointer dereference.
> 
> Was largely found by using a static code analysis program called cppcheck.
> 
> Signed-off-by: Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
> ---
>  drivers/staging/unisys/virtpci/virtpci.c |   23 +++++++++--------------
>  1 file changed, 9 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/staging/unisys/virtpci/virtpci.c b/drivers/staging/unisys/virtpci/virtpci.c
> index ee9f826..d818eda 100644
> --- a/drivers/staging/unisys/virtpci/virtpci.c
> +++ b/drivers/staging/unisys/virtpci/virtpci.c
> @@ -1314,15 +1314,13 @@ static ssize_t virtpci_driver_attr_show(struct kobject *kobj,
>  	ssize_t ret = 0;
>  
>  	struct driver_private *dprivate = to_driver(kobj);
> -	struct device_driver *driver;
>  
> -	if (dprivate != NULL)
> -		driver = dprivate->driver;
> -	else
> -		driver = NULL;
> +	if (dprivate) {

It is impossible for dprivate to ever be NULL, someone doesn't
understand how kobjects work :(

So just remove the check please, don't add more logic that will never
run.

thanks,

greg k-h
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