comedi: pcmda12: Add sanity checks for I/O base address

The "pcmda12" driver uses an admin-supplied configuration option
(`it->options[0]`) to configure the I/O port base address of a
PCM-D/A-12 or PCM-A/D-16 board.  It currently allows any base address to
be configured.  I cannot find a full manual, but the short datasheet
says it uses 15 consecutive I/O addresses on "any even sixteen port
boundary", so assume it supports base addresses (configured by on-board
jumpers) in the range 0 to 0x3E0 on 32-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>
Link: https://patch.msgid.link/20260130170416.49994-42-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/comedi/drivers/pcmda12.c b/drivers/comedi/drivers/pcmda12.c
index 611f13bedca058edb1d38cf93cb007e239eb9ed9..6efd1ae6271a8e38f1155b768fd8a0224e9c5ec9 100644 (file)
--- a/drivers/comedi/drivers/pcmda12.c
+++ b/drivers/comedi/drivers/pcmda12.c
@@ -120,7 +120,14 @@ static int pcmda12_attach(struct comedi_device *dev,
        struct comedi_subdevice *s;
        int ret;
 
-       ret = comedi_request_region(dev, it->options[0], 0x10);
+       /*
+        * The datasheet says it requires 16 contiguous addresses and is
+        * "configurable on any even sixteen port boundary".  So require
+        * a 32-byte boundary and assume it uses 10-bit addresses like
+        * similar boards.
+        */
+       ret = comedi_check_request_region(dev, it->options[0], 0x10,
+                                         0, 0x3ff, 32);
        if (ret)
                return ret;