comedi: pcmmio: validate the IRQ supplied by userspace

comedi boards are configured through the COMEDI_DEVCONFIG ioctl, so
it->options[1] is a number chosen by userspace. pcmmio 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 board's interrupt is routed in software rather than jumpered, and the
driver notes that "any IRQ from 1-15 is OK", so the ISA range is exactly
the right bound.

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: 6baef150380d ("Staging: comedi: add pcmmio and pcmuio drivers")
Assisted-by: LLM
Signed-off-by: Yogesh Gaur <yogeshgaur.83@gmail.com>
Link: https://patch.msgid.link/20260909104848.1763-6-yogeshgaur.83@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

0 files changed, 0 insertions, 0 deletions