diff options
authorIan Abbott <>2019-06-26 14:18:04 +0100
committerGreg Kroah-Hartman <>2019-07-14 08:11:20 +0200
commit4e49c6c91c18330409bd5181ccf73c6382e72c0b (patch)
parent8419fd562a091a1d6a69caa63cfff34510b4f474 (diff)
staging: comedi: dt282x: fix a null pointer deref on interrupt
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: comedi_handle_events(dev, s_ao); 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.) Note: commit 4f6f009b204f ("staging: comedi: dt282x: use comedi_handle_events()") propagates an earlier error from commit f21c74fa4cfe ("staging: comedi: dt282x: use cfc_handle_events()"). Fixes: 4f6f009b204f ("staging: comedi: dt282x: use comedi_handle_events()") Cc: <> # v3.19+ Signed-off-by: Ian Abbott <> Signed-off-by: Greg Kroah-Hartman <>
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/staging/comedi/drivers/dt282x.c b/drivers/staging/comedi/drivers/dt282x.c
index 3be927f1d3a9..e15e33ed94ae 100644
--- a/drivers/staging/comedi/drivers/dt282x.c
+++ b/drivers/staging/comedi/drivers/dt282x.c
@@ -557,7 +557,8 @@ static irqreturn_t dt282x_interrupt(int irq, void *d)
comedi_handle_events(dev, s);
- comedi_handle_events(dev, s_ao);
+ if (s_ao)
+ comedi_handle_events(dev, s_ao);
return IRQ_RETVAL(handled);