linux-kernel - [PATCH 09/46] comedi: c6xdigio: Add sanity checks for I/O base address

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Message-ID: <20260130170416.49994-10-abbotti@mev.co.uk>
Date: Fri, 30 Jan 2026 16:47:34 +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 09/46] comedi: c6xdigio: Add sanity checks for I/O base address

The "c6xdigio" driver uses an admin-supplied configuration option
(`it->options[0]`) to configure the I/O port base address of a supported
C6x_DIGIO DSP device connected to a PC printer parallel port (driving
the port's I/O registers directly).  Currently, the driver allows any
I/O base address to be specified as long as the I/O region can be
reserved, and it converts the specified `int` option value holding the
base address to `unsigned long`.

It doesn't make sense to allow base addresses that are not aligned to
4-byte boundaries (for SPP printer ports, although printer ports with
EPP/ECP support actually need to be aligned on 8-byte boundaries), so
add a check for 4-byte alignment.

Convert the option value that specifies the base address from `int` to
`unsigned int` instead of `unsigned long` so it ends up the same on
32-bit and 64-bit systems.

Signed-off-by: Ian Abbott <abbotti@....co.uk>
---
 drivers/comedi/drivers/c6xdigio.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/comedi/drivers/c6xdigio.c b/drivers/comedi/drivers/c6xdigio.c
index 8a38d97d463b..b6563a48ada6 100644
--- a/drivers/comedi/drivers/c6xdigio.c
+++ b/drivers/comedi/drivers/c6xdigio.c
@@ -239,9 +239,11 @@ static int c6xdigio_attach(struct comedi_device *dev,
 			   struct comedi_devconfig *it)
 {
 	struct comedi_subdevice *s;
+	unsigned int iobase = it->options[0];
 	int ret;

-	ret = comedi_request_region(dev, it->options[0], 0x03);
+	ret = comedi_check_request_region(dev, iobase, 0x03,
+					  0, UINT_MAX, 4);
 	if (ret)
 		return ret;

-- 
2.51.0