`dio200_detach()` is called by the comedi core to clean up if either
`dio200_attach()` or `dio200_attach_pci()` return an error. It assigns
`thisboard` to the return value of `comedi_board(dev)` and assumes it is
non-null. In the case of a previous call to `dio200_attach()` it won't
be `NULL` because the comedi core will have pointed it to one of the
elements of `dio200_boards[]`, but in the case of a previous call to
`dio200_attach_pci()` it could be `NULL`, leading to a null pointer
dereference.
Check that `thisboard` is valid at the top of `dio200_detach()` and
return early if it is `NULL`. This is okay because the only other thing
that could have been allocated is `dev->private` and that is freed by
the comedi core, not by this function.
Cc: <stable@xxxxxxxxxxxxxxx> # 3.6.x
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
---
drivers/staging/comedi/drivers/amplc_dio200.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/staging/comedi/drivers/amplc_dio200.c b/drivers/staging/comedi/drivers/amplc_dio200.c
index 08f3052..29eb52d 100644
--- a/drivers/staging/comedi/drivers/amplc_dio200.c
+++ b/drivers/staging/comedi/drivers/amplc_dio200.c
@@ -1410,6 +1410,8 @@ static void dio200_detach(struct comedi_device *dev)
const struct dio200_layout_struct *layout;
unsigned n;
+ if (!thisboard)
+ return;
if (dev->irq)
free_irq(dev->irq, dev);
if (dev->subdevices) {
--
1.7.12
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