From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933142Ab3B1PSg (ORCPT ); Thu, 28 Feb 2013 10:18:36 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:41994 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756153Ab3B1OrB (ORCPT ); Thu, 28 Feb 2013 09:47:01 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Ian Abbott , Greg Kroah-Hartman , Luis Henriques Subject: [PATCH 031/139] staging: comedi: check s->async for poll(), read() and write() Date: Thu, 28 Feb 2013 14:43:01 +0000 Message-Id: <1362062689-2567-32-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1362062689-2567-1-git-send-email-luis.henriques@canonical.com> References: <1362062689-2567-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.5.7.7 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Ian Abbott commit cc400e185c07c15a42d2635995f422de5b94b696 upstream. Some low-level comedi drivers (incorrectly) point `dev->read_subdev` or `dev->write_subdev` to a subdevice that does not support asynchronous commands. Comedi's poll(), read() and write() file operation handlers assume these subdevices do support asynchronous commands. In particular, they assume `s->async` is valid (where `s` points to the read or write subdevice), which it won't be if it has been set incorrectly. This can lead to a NULL pointer dereference. Check `s->async` is non-NULL in `comedi_poll()`, `comedi_read()` and `comedi_write()` to avoid the bug. Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman [ luis: adjust context, variables names ] Signed-off-by: Luis Henriques --- drivers/staging/comedi/comedi_fops.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index 2831080..b08cbbe 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -1866,7 +1866,7 @@ static unsigned int comedi_poll(struct file *file, poll_table *wait) mask = 0; read_subdev = comedi_get_read_subdevice(dev_file_info); - if (read_subdev) { + if (read_subdev && read_subdev->async) { poll_wait(file, &read_subdev->async->wait_head, wait); if (!read_subdev->busy || comedi_buf_read_n_available(read_subdev->async) > 0 @@ -1876,7 +1876,7 @@ static unsigned int comedi_poll(struct file *file, poll_table *wait) } } write_subdev = comedi_get_write_subdevice(dev_file_info); - if (write_subdev) { + if (write_subdev && write_subdev->async) { poll_wait(file, &write_subdev->async->wait_head, wait); comedi_buf_write_alloc(write_subdev->async, write_subdev->async->prealloc_bufsz); @@ -1918,7 +1918,7 @@ static ssize_t comedi_write(struct file *file, const char __user *buf, } s = comedi_get_write_subdevice(dev_file_info); - if (s == NULL) { + if (!s || !s->async) { retval = -EIO; goto done; } @@ -2029,7 +2029,7 @@ static ssize_t comedi_read(struct file *file, char __user *buf, size_t nbytes, } s = comedi_get_read_subdevice(dev_file_info); - if (s == NULL) { + if (!s || !s->async) { retval = -EIO; goto done; } -- 1.8.1.2