Commit b14b076c authored by Ian Abbott's avatar Ian Abbott Committed by Greg Kroah-Hartman
Browse files

comedi: pcl812: Fix bit shift out of bounds 



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

	if ((1 << it->options[1]) & board->irq_bits) {

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.

Reported-by: default avatar <syzbot+32de323b0addb9e114ff@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=32de323b0addb9e114ff


Fixes: fcdb427b ("Staging: comedi: add pcl821 driver")
Cc: stable@vger.kernel.org # 5.13+
Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/20250707133429.73202-1-abbotti@mev.co.uk


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ed93c6f6

drivers/comedi/drivers/pcl812.c

+2 −1
Original line number Diff line number Diff line
@@ -1149,7 +1149,8 @@ static int pcl812_attach(struct comedi_device *dev, struct comedi_devconfig *it) 
		if (IS_ERR(dev->pacer))

			return PTR_ERR(dev->pacer);



		if ((1 << it->options[1]) & board->irq_bits) {

		if (it->options[1] > 0 && it->options[1] < 16 &&

		    (1 << it->options[1]) & board->irq_bits) {

			ret = request_irq(it->options[1], pcl812_interrupt, 0,

					  dev->board_name, dev);

			if (ret == 0)