From: Marc Kleine-Budde [ 

On 09/15/2014 10:28 AM, David Laight wrote:

quoted

From: Rickard Strandqvist
...

quoted

Replacing strncpy with strlcpy to avoid strings that lacks null terminate.

...

quoted

diff --git a/drivers/net/can/usb/peak_usb/pcan_usb_core.c

b/drivers/net/can/usb/peak_usb/pcan_usb_core.c
index 644e6ab..d4fe8ac 100644

--- a/drivers/net/can/usb/peak_usb/pcan_usb_core.c
+++ b/drivers/net/can/usb/peak_usb/pcan_usb_core.c

@@ -830,7 +830,7 @@ static void peak_usb_disconnect(struct usb_interface *intf)
 		char name[IFNAMSIZ];

 		dev->state &= ~PCAN_USB_STATE_CONNECTED;
-		strncpy(name, netdev->name, IFNAMSIZ);
+		strlcpy(name, netdev->name, IFNAMSIZ);

 		unregister_netdev(netdev);
 		free_candev(netdev);

Or:
	char name[sizeof netdev->name];
	memcpy(name, netdev->name, sizeof netdev->name);

I would be "sizeof(foo)" in kernel coding style,

But not in mine :-)
sizeof is an operator, not a function, it's argument can be (type).

but let's have a look at the original code:

                struct net_device *netdev = dev->netdev;
                char name[IFNAMSIZ];

                dev->state &= ~PCAN_USB_STATE_CONNECTED;
                strncpy(name, netdev->name, IFNAMSIZ);

                unregister_netdev(netdev);
                free_candev(netdev);

                kfree(dev->cmd_buf);
                dev->next_siblings = NULL;
                if (dev->adapter->dev_free)
                        dev->adapter->dev_free(dev);

                dev_info(&intf->dev, "%s removed\n", name);

I think it's save to use:

    dev_info(&intf->dev, "%s removed\n", netdev_name(dev->netdev));

instead of doing the str?cpy() in the first place. But why not use:

    netdev_info(dev->netdev, "removed\n");

Is the USB device information lost when using netdev_info()?

My guess is it avoids a 'use after free' - but I'm not going to
dig that far.

Another issue with blindly replacing strncpy() with strlcpy()
(which doesn't affect the above) is when copying status to userspace.

	David