Subject: Re: [PATCH] can: Fix possible NULL pointer dereference in ems_usb.c

From: "Hans J. Koch" <[email-masked]>
Date: Wed, 21 Apr 2010 12:18:06 +0200

On Tue, Apr 20, 2010 at 06:05:01PM -0700, David Miller wrote:
> From: Wolfgang Grandegger <[email-masked]>
> > I think "dev_err(&intf->dev, ...)" should be used before
> > SET_NETDEV_DEV(netdev, &intf->dev) is called. I see two "dev_err()"
> > calls which need to be fixed.
> 
> Agreed.

Then it should probably look like this:

From: "Hans J. Koch" <[email-masked]>
To: [email-masked]
Cc: [email-masked],
	Sebastian Haas <[email-masked]>
Subject: [PATCH] can: Fix possible NULL pointer dereference in ems_usb.c

In ems_usb_probe(), a pointer is dereferenced after making sure it is NULL...

This patch replaces netdev->dev.parent with &intf->dev in dev_err() calls to
avoid this.

Signed-off-by: "Hans J. Koch" <[email-masked]>
---
 drivers/net/can/usb/ems_usb.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Index: net-next-2.6/drivers/net/can/usb/ems_usb.c
===================================================================
--- net-next-2.6.orig/drivers/net/can/usb/ems_usb.c	2010-04-13 11:27:33.000000000 +0200
+++ net-next-2.6/drivers/net/can/usb/ems_usb.c	2010-04-21 11:59:04.000000000 +0200
@@ -1006,7 +1006,7 @@
 
 	netdev = alloc_candev(sizeof(struct ems_usb), MAX_TX_URBS);
 	if (!netdev) {
-		dev_err(netdev->dev.parent, "Couldn't alloc candev\n");
+		dev_err(&intf->dev, "ems_usb: Couldn't alloc candev\n");
 		return -ENOMEM;
 	}
 
@@ -1036,20 +1036,20 @@
 
 	dev->intr_urb = usb_alloc_urb(0, GFP_KERNEL);
 	if (!dev->intr_urb) {
-		dev_err(netdev->dev.parent, "Couldn't alloc intr URB\n");
+		dev_err(&intf->dev, "Couldn't alloc intr URB\n");
 		goto cleanup_candev;
 	}
 
 	dev->intr_in_buffer = kzalloc(INTR_IN_BUFFER_SIZE, GFP_KERNEL);
 	if (!dev->intr_in_buffer) {
-		dev_err(netdev->dev.parent, "Couldn't alloc Intr buffer\n");
+		dev_err(&intf->dev, "Couldn't alloc Intr buffer\n");
 		goto cleanup_intr_urb;
 	}
 
 	dev->tx_msg_buffer = kzalloc(CPC_HEADER_SIZE +
 				     sizeof(struct ems_cpc_msg), GFP_KERNEL);
 	if (!dev->tx_msg_buffer) {
-		dev_err(netdev->dev.parent, "Couldn't alloc Tx buffer\n");
+		dev_err(&intf->dev, "Couldn't alloc Tx buffer\n");
 		goto cleanup_intr_in_buffer;
 	}