[PATCH 2/6] comedi: ni_atmio16d: validate the IRQ supplied by userspace

[Yogesh Gaur <yogeshgaur.83@gmail.com>]

comedi boards are configured through the COMEDI_DEVCONFIG ioctl, so
it->options[1] is a number chosen by userspace. ni_atmio16d passes it to
request_irq() without checking it first, which lets an interrupt owned by
another irqdomain -- a PCI device's IO-APIC GSI, for instance -- be
claimed for this board. When the owner of that interrupt is later
released the descriptor is freed while this driver's handler is still
installed on it.

The driver already documents which interrupts the board can assert --
"0 == no irq; or 3,4,5,6,7,9,10,11,12,14,15" -- so use exactly that set
rather than the whole ISA range.

Bound the value before requesting it, as das16m1.c already does. An
out-of-range value is ignored rather than rejected, so the board still
attaches without interrupt support, exactly as it does today when
request_irq() fails.

Fixes: 2323b276308a ("Staging: comedi: add ni_at_atmio16d driver")
Assisted-by: LLM
Signed-off-by: Yogesh Gaur <yogeshgaur.83@gmail.com>
---
 drivers/comedi/drivers/ni_atmio16d.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/comedi/drivers/ni_atmio16d.c b/drivers/comedi/drivers/ni_atmio16d.c
index 6765cdc276ca..87fed16b112c 100644
--- a/drivers/comedi/drivers/ni_atmio16d.c
+++ b/drivers/comedi/drivers/ni_atmio16d.c
@@ -593,7 +593,9 @@ static int atmio16d_attach(struct comedi_device *dev,
 	/* reset the atmio16d hardware */
 	reset_atmio16d(dev);
 
-	if (it->options[1]) {
+	/* only irqs 3, 4, 5, 6, 7, 9, 10, 11, 12, 14, and 15 are valid */
+	if (it->options[1] >= 3 && it->options[1] <= 15 &&
+	    (1 << it->options[1]) & 0xdef8) {
 		ret = request_irq(it->options[1], atmio16d_interrupt, 0,
 				  dev->board_name, dev);
 		if (ret == 0)
-- 
2.55.0.windows.5