The "dac02" driver uses an admin-supplied configuration option
(`it->options[0]`) to configure the I/O port base address of a supported
DAC-02 board.  It currently allows any base address to be configured but
the hardware only supports base addresses (configured by an on-board DIP
switch) in the range 0x200 to 0x3f8 on 8-byte boundaries.

Add a sanity check to ensure the device is not configured at an
unsupported base address.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
---
 drivers/comedi/drivers/dac02.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/comedi/drivers/dac02.c b/drivers/comedi/drivers/dac02.c
index 4b011d66d7b0..2c04472c5078 100644
--- a/drivers/comedi/drivers/dac02.c
+++ b/drivers/comedi/drivers/dac02.c
@@ -103,7 +103,8 @@ static int dac02_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 	struct comedi_subdevice *s;
 	int ret;
 
-	ret = comedi_request_region(dev, it->options[0], 0x08);
+	ret = comedi_check_request_region(dev, it->options[0], 0x08,
+					  0x200, 0x3ff, 8);
 	if (ret)
 		return ret;
 
-- 
2.51.0