linux-kernel - [PATCH 34/46] comedi: pcl726: Add sanity checks for I/O base address

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Message-ID: <20260130170416.49994-35-abbotti@mev.co.uk>
Date: Fri, 30 Jan 2026 16:47:59 +0000
From: Ian Abbott <abbotti@....co.uk>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Ian Abbott <abbotti@....co.uk>,
	H Hartley Sweeten <hsweeten@...ionengravers.com>
Subject: [PATCH 34/46] comedi: pcl726: Add sanity checks for I/O base address

The "pcl726" driver uses an admin-supplied configuration option
(`it->options[0]`) to configure the I/O port base address of various
analog output ISA boards from Advantech (PCL-726/727/728) and ADLINK
(ACL-6126/6128).  (Most of them also have digital I/O.)  It currently
allows any base address to be configured but the hardware only supports
base addresses (configured by on-board DIP switches) from 0 or 0x200 up
to nearly 0x3FF, depending on the model.

Store the minimum and maximum supported I/O address ranges in the static
board information array elements (the required alignment is already
stored in the `io_len` member), and add a sanity check to ensure the
device is not configured at an unsupported base address.

Signed-off-by: Ian Abbott <abbotti@....co.uk>
---
 drivers/comedi/drivers/pcl726.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/comedi/drivers/pcl726.c b/drivers/comedi/drivers/pcl726.c
index b542896fa0e4..d3b1f4388643 100644
--- a/drivers/comedi/drivers/pcl726.c
+++ b/drivers/comedi/drivers/pcl726.c
@@ -91,7 +91,8 @@ static const struct comedi_lrange *const rangelist_728[] = {
 
 struct pcl726_board {
 	const char *name;
-	unsigned long io_len;
+	unsigned int io_len;
+	unsigned int min_io_start;
 	unsigned int irq_mask;
 	const struct comedi_lrange *const *ao_ranges;
 	int ao_num_ranges;
@@ -104,6 +105,7 @@ static const struct pcl726_board pcl726_boards[] = {
 	{
 		.name		= "pcl726",
 		.io_len		= 0x10,
+		.min_io_start	= 0x200,
 		.ao_ranges	= &rangelist_726[0],
 		.ao_num_ranges	= ARRAY_SIZE(rangelist_726),
 		.ao_nchan	= 6,
@@ -111,6 +113,7 @@ static const struct pcl726_board pcl726_boards[] = {
 	}, {
 		.name		= "pcl727",
 		.io_len		= 0x20,
+		.min_io_start	= 0x200,
 		.ao_ranges	= &rangelist_727[0],
 		.ao_num_ranges	= ARRAY_SIZE(rangelist_727),
 		.ao_nchan	= 12,
@@ -119,12 +122,14 @@ static const struct pcl726_board pcl726_boards[] = {
 	}, {
 		.name		= "pcl728",
 		.io_len		= 0x08,
+		.min_io_start	= 0,
 		.ao_num_ranges	= ARRAY_SIZE(rangelist_728),
 		.ao_ranges	= &rangelist_728[0],
 		.ao_nchan	= 2,
 	}, {
 		.name		= "acl6126",
 		.io_len		= 0x10,
+		.min_io_start	= 0x200,
 		.irq_mask	= 0x96e8,
 		.ao_num_ranges	= ARRAY_SIZE(rangelist_726),
 		.ao_ranges	= &rangelist_726[0],
@@ -133,6 +138,7 @@ static const struct pcl726_board pcl726_boards[] = {
 	}, {
 		.name		= "acl6128",
 		.io_len		= 0x08,
+		.min_io_start	= 0,
 		.ao_num_ranges	= ARRAY_SIZE(rangelist_728),
 		.ao_ranges	= &rangelist_728[0],
 		.ao_nchan	= 2,
@@ -316,7 +322,9 @@ static int pcl726_attach(struct comedi_device *dev,
 	int ret;
 	int i;
 
-	ret = comedi_request_region(dev, it->options[0], board->io_len);
+	ret = comedi_check_request_region(dev, it->options[0], board->io_len,
+					  board->min_io_start, 0x3ff,
+					  board->io_len);
 	if (ret)
 		return ret;
 
-- 
2.51.0