comedi: 8255: Add some I/O base address sanity checks

The "8255" driver allows a COMEDI device to be constructed from one or
more 8255 chips, each at an I/O port base address specified by the
admin-supplied configuration options (`it->options[]`).  Currently, the
driver allows any I/O base addresses to be specified as long as the I/O
regions can be reserved, and it converts the specified `int` option
values holding the base address to `unsigned long`.

It doesn't make sense to allow base addresses that are not aligned to
4-byte boundaries because the hardware register addresses would not be
decoded properly, so add a check for valid alignment.

Convert the option values that specify the base addresses from `int` to
`unsigned int` instead of `unsigned long` so they end up the same on
32-bit and 64-bit systems.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://patch.msgid.link/20260130170416.49994-3-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/comedi/drivers/8255.c b/drivers/comedi/drivers/8255.c
index 5f70938b44773821e70965b5b49c23232e1b3f10..ff45248ebb2973207901e0ad0fc08f2e7aeb55cc 100644 (file)
--- a/drivers/comedi/drivers/8255.c
+++ b/drivers/comedi/drivers/8255.c
@@ -47,7 +47,7 @@ static int dev_8255_attach(struct comedi_device *dev,
                           struct comedi_devconfig *it)
 {
        struct comedi_subdevice *s;
-       unsigned long iobase;
+       unsigned int iobase;
        int ret;
        int i;
 
@@ -70,13 +70,15 @@ static int dev_8255_attach(struct comedi_device *dev,
                iobase = it->options[i];
 
                /*
-                * __comedi_request_region() does not set dev->iobase.
+                * __comedi_check_request_region() does not set dev->iobase.
                 *
                 * For 8255 devices that are manually attached using
                 * comedi_config, the 'iobase' is the actual I/O port
-                * base address of the chip.
+                * base address of the chip.  It should be aligned on
+                * a 4-byte boundary.
                 */
-               ret = __comedi_request_region(dev, iobase, I8255_SIZE);
+               ret = __comedi_check_request_region(dev, iobase, I8255_SIZE,
+                                                   0, UINT_MAX, 4);
                if (ret)
                        return ret;
                ret = subdev_8255_io_init(dev, s, iobase);