commit b8336be66dec06bef518030a0df9847122053ec5 upstream.
The interrupt handler `dt282x_interrupt()` causes a null pointer
dereference for those supported boards that have no analog output
support. For these boards, `dev->write_subdev` will be `NULL` and
therefore the `s_ao` subdevice pointer variable will be `NULL`. In that
case, the following call near the end of the interrupt handler results
in a null pointer dereference:
cfc_handle_events(dev, s_ao);
[ Upstream equivalent:
comedi_handle_events(dev, s_ao);
-- IA ]
Fix it by only calling the above function if `s_ao` is valid.
(There are other uses of `s_ao` by the interrupt handler that may or may
not be reached depending on values of hardware registers. Trust that
they are reliable for now.)
Fixes: f21c74fa4cfe ("staging: comedi: dt282x: use cfc_handle_events()")
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/staging/comedi/drivers/dt282x.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/staging/comedi/drivers/dt282x.c b/drivers/staging/comedi/drivers/dt282x.c
index c2a66dcf99fe..6a1222c45d35 100644
--- a/drivers/staging/comedi/drivers/dt282x.c
+++ b/drivers/staging/comedi/drivers/dt282x.c
@@ -483,7 +483,8 @@ static irqreturn_t dt282x_interrupt(int irq, void *d)
}
#endif
cfc_handle_events(dev, s);
- cfc_handle_events(dev, s_ao);
+ if (s_ao)
+ cfc_handle_events(dev, s_ao);
return IRQ_RETVAL(handled);
}
--
2.20.1
