Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755197Ab3CAUND (ORCPT ); Fri, 1 Mar 2013 15:13:03 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:51560 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753089Ab3CATpq (ORCPT ); Fri, 1 Mar 2013 14:45:46 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ian Abbott Subject: [ 68/77] staging: comedi: check s->async for poll(), read() and write() Date: Fri, 1 Mar 2013 11:44:53 -0800 Message-Id: <20130301194359.150597501@linuxfoundation.org> X-Mailer: git-send-email 1.8.1.rc1.5.g7e0651a In-Reply-To: <20130301194351.913471337@linuxfoundation.org> References: <20130301194351.913471337@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 Content-Length: 2439 Lines: 71 3.8-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 --- drivers/staging/comedi/comedi_fops.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -1779,7 +1779,7 @@ static unsigned int comedi_poll(struct f 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 @@ -1789,7 +1789,7 @@ static unsigned int comedi_poll(struct f } } 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); @@ -1831,7 +1831,7 @@ static ssize_t comedi_write(struct file } s = comedi_get_write_subdevice(dev_file_info); - if (s == NULL) { + if (s == NULL || s->async == NULL) { retval = -EIO; goto done; } @@ -1942,7 +1942,7 @@ static ssize_t comedi_read(struct file * } s = comedi_get_read_subdevice(dev_file_info); - if (s == NULL) { + if (s == NULL || s->async == NULL) { retval = -EIO; goto done; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/