From: Ian Abbott <abbotti@xxxxxxxxx>
commit 7379e6baeddf580d01feca650ec1ad508b6ea8ee upstream.
The interrupt handler `pci230_interrupt()` causes a null pointer
dereference for a PCI260 card. There is no analog output subdevice for
a PCI260. The `dev->write_subdev` subdevice pointer and therefore the
`s_ao` subdevice pointer variable will be `NULL` for a PCI260. The
following call near the end of the interrupt handler results in the null
pointer dereference for a PCI260:
comedi_handle_events(dev, s_ao);
Fix it by only calling the above function if `s_ao` is valid.
Note that the other uses of `s_ao` in the calls
`pci230_handle_ao_nofifo(dev, s_ao);` and `pci230_handle_ao_fifo(dev,
s_ao);` will never be reached for a PCI260, so they are safe.
Fixes: 39064f23284c ("staging: comedi: amplc_pci230: use comedi_handle_events()")
Cc: <stable@xxxxxxxxxxxxxxx> # v3.19+
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/staging/comedi/drivers/amplc_pci230.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/staging/comedi/drivers/amplc_pci230.c
+++ b/drivers/staging/comedi/drivers/amplc_pci230.c
@@ -2339,7 +2339,8 @@ static irqreturn_t pci230_interrupt(int
devpriv->intr_running = false;
spin_unlock_irqrestore(&devpriv->isr_spinlock, irqflags);
- comedi_handle_events(dev, s_ao);
+ if (s_ao)
+ comedi_handle_events(dev, s_ao);
comedi_handle_events(dev, s_ai);
return IRQ_HANDLED;
