The "dt2801" driver uses an admin-supplied configuration option
(`it->options[0]`) to configure the I/O port base address of a supported
board in the DT2801 family.  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 0x3fe on 2-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/dt2801.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/comedi/drivers/dt2801.c b/drivers/comedi/drivers/dt2801.c
index 230d25010f58..d790e69f98a0 100644
--- a/drivers/comedi/drivers/dt2801.c
+++ b/drivers/comedi/drivers/dt2801.c
@@ -540,7 +540,8 @@ static int dt2801_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 	int ret = 0;
 	int n_ai_chans;
 
-	ret = comedi_request_region(dev, it->options[0], 0x2);
+	ret = comedi_check_request_region(dev, it->options[0], 0x2,
+					  0x200, 0x3ff, 2);
 	if (ret)
 		return ret;
 
-- 
2.51.0