From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ian Abbott , Dan Carpenter Subject: [PATCH 3.4 27/31] staging: comedi: pcmuio: fix possible NULL deref on detach Date: Wed, 18 Dec 2013 13:08:35 -0800 Message-Id: <20131218210523.549723497@linuxfoundation.org> In-Reply-To: <20131218210522.790152625@linuxfoundation.org> References: <20131218210522.790152625@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ian Abbott commit 2fd2bdfccae61efe18f6b92b6a45fbf936d75b48 upstream. pcmuio_detach() is called by the comedi core even if pcmuio_attach() returned an error, so `dev->private` might be `NULL`. Check for that before dereferencing it. Also, as pointed out by Dan Carpenter, there is no need to check the pointer passed to `kfree()` is non-NULL, so remove that check. Signed-off-by: Ian Abbott Cc: Dan Carpenter Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/drivers/pcmuio.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/drivers/staging/comedi/drivers/pcmuio.c +++ b/drivers/staging/comedi/drivers/pcmuio.c @@ -464,13 +464,13 @@ static int pcmuio_detach(struct comedi_d if (dev->iobase) release_region(dev->iobase, ASIC_IOSIZE * thisboard->num_asics); - for (i = 0; i < MAX_ASICS; ++i) { - if (devpriv->asics[i].irq) - free_irq(devpriv->asics[i].irq, dev); - } - - if (devpriv && devpriv->sprivs) + if (devpriv) { + for (i = 0; i < MAX_ASICS; ++i) { + if (devpriv->asics[i].irq) + free_irq(devpriv->asics[i].irq, dev); + } kfree(devpriv->sprivs); + } return 0; }