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: [e-mail] # 5.13+
Signed-off-by: Ian Abbott <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/comedi/drivers/aio_iiro_16.c

···
 	 * 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)