[PATCH 10/11] comedi: pcmuio: Add sanity check to interrupt handler

[Ian Abbott]

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
pcmuio_interrupt() to ensure the device has been fully set up, avoiding
a possible null pointer dereference of dev->subdevices by
pcmuio_handle_asic_interrupt().

Also make use of the IRQ_HANDLED(x) macro for the normal return path of
the interrupt handler.

Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
---
 drivers/comedi/drivers/pcmuio.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/comedi/drivers/pcmuio.c b/drivers/comedi/drivers/pcmuio.c
index 0995911a3ea30..d9995cbeecb62 100644
--- a/drivers/comedi/drivers/pcmuio.c
+++ b/drivers/comedi/drivers/pcmuio.c
@@ -362,12 +362,15 @@ static irqreturn_t pcmuio_interrupt(int irq, void *d)
 	struct pcmuio_private *devpriv = dev->private;
 	int handled = 0;
 
+	if (!dev->attached)
+		return IRQ_NONE;
+
 	if (irq == dev->irq)
 		handled += pcmuio_handle_asic_interrupt(dev, 0);
 	if (irq == devpriv->irq2)
 		handled += pcmuio_handle_asic_interrupt(dev, 1);
 
-	return handled ? IRQ_HANDLED : IRQ_NONE;
+	return IRQ_RETVAL(handled);
 }
 
 /* chip->spinlock is already locked */
-- 
2.53.0