From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761271Ab2J2WNl (ORCPT ); Mon, 29 Oct 2012 18:13:41 -0400 Received: from mail.kernel.org ([198.145.19.201]:47454 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761199Ab2J2VhJ (ORCPT ); Mon, 29 Oct 2012 17:37:09 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , alan@lxorguk.ukuu.org.uk, Ian Abbott Subject: [ 031/101] staging: comedi: amplc_dio200: fix possible NULL deref during detach Date: Mon, 29 Oct 2012 14:34:44 -0700 Message-Id: <20121029213243.670493260@linuxfoundation.org> X-Mailer: git-send-email 1.7.12.2.421.g261b511 In-Reply-To: <20121029213240.128426598@linuxfoundation.org> References: <20121029213240.128426598@linuxfoundation.org> User-Agent: quilt/0.60-2.1.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ian Abbott commit dfb2540e91e1f63765bc3ff497ad0b714d774261 upstream. `dio200_detach()` is called by the comedi core to clean up if either `dio200_attach()` or `dio200_attach_pci()` return an error. It assigns `thisboard` to the return value of `comedi_board(dev)` and assumes it is non-null. In the case of a previous call to `dio200_attach()` it won't be `NULL` because the comedi core will have pointed it to one of the elements of `dio200_boards[]`, but in the case of a previous call to `dio200_attach_pci()` it could be `NULL`, leading to a null pointer dereference. Check that `thisboard` is valid at the top of `dio200_detach()` and return early if it is `NULL`. This is okay because the only other thing that could have been allocated is `dev->private` and that is freed by the comedi core, not by this function. Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/drivers/amplc_dio200.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/staging/comedi/drivers/amplc_dio200.c +++ b/drivers/staging/comedi/drivers/amplc_dio200.c @@ -1429,6 +1429,8 @@ static void dio200_detach(struct comedi_ const struct dio200_layout_struct *layout; unsigned n; + if (!thisboard) + return; if (dev->irq) free_irq(dev->irq, dev); if (dev->subdevices) {