USB: chaoskey: Use kasprintf() over strcpy()/strcat()

Instead of kmalloc() with manually calculated values followed by
multiple strcpy()/strcat() calls, just fold it all into a single
kasprintf() call.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/misc/chaoskey.c

@@ -168,14 +168,10 @@ static int chaoskey_probe(struct usb_interface *interface,
 	 */
 
 	if (udev->product && udev->serial) {
-		dev->name = kmalloc(strlen(udev->product) + 1 +
-				    strlen(udev->serial) + 1, GFP_KERNEL);
+		dev->name = kasprintf(GFP_KERNEL, "%s-%s", udev->product,
+				      udev->serial);
 		if (dev->name == NULL)
 			goto out;
-
-		strcpy(dev->name, udev->product);
-		strcat(dev->name, "-");
-		strcat(dev->name, udev->serial);
 	}
 
 	dev->interface = interface;