[PATCH] staging: unisys: virtpci: virtpci.c: Fix for possible null pointer dereference

[PATCH] staging: unisys: virtpci: virtpci.c: Fix for possible null pointer dereference

[Rickard Strandqvist]

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@spectrumdigital.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) {
+		struct device_driver *driver = dprivate->driver;
+
+		DBGINF("In virtpci_driver_attr_show driver->name:%s\n",
+				driver->name);
 
-	DBGINF("In virtpci_driver_attr_show driver->name:%s\n", driver->name);
-	if (driver) {
 		if (dattr->show)
 			ret = dattr->show(driver, buf);
 	}
@@ -1337,16 +1335,13 @@ static ssize_t virtpci_driver_attr_store(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) {
+		struct device_driver *driver = dprivate->driver;
 
-	DBGINF("In virtpci_driver_attr_store driver->name:%s\n", driver->name);
+		DBGINF("In virtpci_driver_attr_store driver->name:%s\n",
+				driver->name);
 
-	if (driver) {
 		if (dattr->store)
 			ret = dattr->store(driver, buf, count);
 	}
-- 
1.7.10.4

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

[Greg Kroah-Hartman]

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@spectrumdigital.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