5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ian Abbott abbotti@mev.co.uk
commit b14b076ce593f72585412fc7fd3747e03a5e3632 upstream.
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: syzbot+32de323b0addb9e114ff@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=32de323b0addb9e114ff Fixes: fcdb427bc7cf ("Staging: comedi: add pcl821 driver") Cc: stable@vger.kernel.org # 5.13+ Signed-off-by: Ian Abbott abbotti@mev.co.uk Link: https://lore.kernel.org/r/20250707133429.73202-1-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/staging/comedi/drivers/pcl812.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/staging/comedi/drivers/pcl812.c +++ b/drivers/staging/comedi/drivers/pcl812.c @@ -1151,7 +1151,8 @@ static int pcl812_attach(struct comedi_d if (!dev->pacer) return -ENOMEM;
- 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)