From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: 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: [ 028/101] staging: comedi: das08: fix possible NULL deref during detach Date: Mon, 29 Oct 2012 14:34:41 -0700 Message-Id: <20121029213243.341990180@linuxfoundation.org> In-Reply-To: <20121029213240.128426598@linuxfoundation.org> References: <20121029213240.128426598@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ian Abbott commit ee280d134f2e05e0172369a53fbe202dbfc527fa upstream. `das08_detach()` is called by the comedi core to clean up if either `das08_attach()` or `das08_attach_pci()` returns an error. It sets `thisboard` to the return value of `comedi_board(dev)` and assumes it is non-null. This is a valid assumption if `das08_attach()` fails, but not if `das08_attach_pci()` fails, leading to a possible NULL pointer dereference. Check `thisboard` at the top of `das08_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/das08.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/staging/comedi/drivers/das08.c +++ b/drivers/staging/comedi/drivers/das08.c @@ -1028,6 +1028,8 @@ static void __maybe_unused das08_detach( const struct das08_board_struct *thisboard = comedi_board(dev); struct das08_private_struct *devpriv = dev->private; + if (!thisboard) + return; das08_common_detach(dev); if (IS_ENABLED(CONFIG_COMEDI_DAS08_ISA) && (thisboard->bustype == isa || thisboard->bustype == pc104)) {