From ea72e2fc9026f375314421ddfa4dbdc49432a899 Mon Sep 17 00:00:00 2001 From: Ian Abbott Date: Thu, 18 Jun 2026 11:09:16 +0100 Subject: [PATCH] comedi: pcmmio: Add sanity check to interrupt handler The driver requests an interrupt handler for the device, after setting device registers to disable interrupt generation. The interrupt handler should not be called prematurely unless the user-configured I/O port base address and/or IRQ number are incorrect or the hardware is bad. For safety, check the dev->attached flag in the interrupt handler to ensure the device has been fully set up, avoiding a possible null pointer dereference of dev->read_subdev. Reported-by: Jaeyoung Chung Link: https://lore.kernel.org/lkml/20260610115912.780131-1-jjy600901@snu.ac.kr/ Reported-by: Sangyun Kim Reported-by: Kyungwook Boo Signed-off-by: Ian Abbott Link: https://patch.msgid.link/20260618102949.26607-10-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman --- drivers/comedi/drivers/pcmmio.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/comedi/drivers/pcmmio.c b/drivers/comedi/drivers/pcmmio.c index d38202c8a12b..f42b7343b4e4 100644 --- a/drivers/comedi/drivers/pcmmio.c +++ b/drivers/comedi/drivers/pcmmio.c @@ -362,6 +362,9 @@ static irqreturn_t interrupt_pcmmio(int irq, void *d) unsigned int triggered; unsigned char int_pend; + if (!dev->attached) + return IRQ_NONE; + /* are there any interrupts pending */ int_pend = inb(dev->iobase + PCMMIO_INT_PENDING_REG) & 0x07; if (!int_pend)