Merge tag 'firewire-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394

Pull firewire fix from Stefan Richter:
 "IEEE 1394 (FireWire) subsystem fix: The character device file
  interface for raw 1394 I/O took uninitialized kernel stack as
  substitute for missing ioctl() argument data.  This could partially
  show up in subsequent read() output"

* tag 'firewire-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
  firewire: cdev: prevent kernel stack leaking into ioctl arguments

drivers/firewire/core-cdev.c

@@ -1637,8 +1637,7 @@ static int dispatch_ioctl(struct client *client,
 	    _IOC_SIZE(cmd) > sizeof(buffer))
 		return -ENOTTY;
 
-	if (_IOC_DIR(cmd) == _IOC_READ)
-		memset(&buffer, 0, _IOC_SIZE(cmd));
+	memset(&buffer, 0, sizeof(buffer));
 
 	if (_IOC_DIR(cmd) & _IOC_WRITE)
 		if (copy_from_user(&buffer, arg, _IOC_SIZE(cmd)))