comedi: aio_iiro_16: Fix bit shift out of bounds

comedi: aio_iiro_16: Fix bit shift out of bounds

commit 66acb1586737a22dd7b78abc63213b1bcaa100e4 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>