From: Ian Abbott abbotti@mev.co.uk
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@vger.kernel.org # v3.19+ Signed-off-by: Ian Abbott abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- 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;