comedi: aio_iiro_16: Fix bit shift out of bounds

When checking for a supported IRQ number, the following test is used:

	if ((1 << it->options[1]) & 0xdcfc) {

However, `it->options[i]` is an unchecked `int` value from userspace, so
the shift amount could be negative or out of bounds.  Fix the test by
requiring `it->options[1]` to be within bounds before proceeding with
the original test.  Valid `it->options[1]` values that select the IRQ
will be in the range [1,15]. The value 0 explicitly disables the use of
interrupts.

Fixes: ad7a370c8be4 ("staging: comedi: aio_iiro_16: add command support for change of state detection")
Cc: stable@vger.kernel.org # 5.13+
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/20250707134622.75403-1-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/comedi/drivers/aio_iiro_16.c b/drivers/comedi/drivers/aio_iiro_16.c
index b00fab0b89d4c45c4cddec4954b82302dcb1b42a..739cc4db52ac7e9d030b2e7d7d3d057041b79f54 100644 (file)
--- a/drivers/comedi/drivers/aio_iiro_16.c
+++ b/drivers/comedi/drivers/aio_iiro_16.c
@@ -177,7 +177,8 @@ static int aio_iiro_16_attach(struct comedi_device *dev,
         * Digital input change of state interrupts are optionally supported
         * using IRQ 2-7, 10-12, 14, or 15.
         */
-       if ((1 << it->options[1]) & 0xdcfc) {
+       if (it->options[1] > 0 && it->options[1] < 16 &&
+           (1 << it->options[1]) & 0xdcfc) {
                ret = request_irq(it->options[1], aio_iiro_16_cos, 0,
                                  dev->board_name, dev);
                if (ret == 0)