`labpc_common_detach()` is called by the comedi core to clean up if
either `labpc_attach()` (including the one in the "ni_labpc_cs" module)
or `labpc_attach_pci()` returns an error. It assumes the `thisboard`
macro (expanding to `((struct labpc_board_struct *)dev->board_ptr)`) is
non-null. This is a valid assumption if `labpc_attach()` fails, but not
if `labpc_attach_pci()` fails, leading to a possible NULL pointer
dereference.
Check `thisboard` at the top of `labpc_common_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/ni_labpc.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/staging/comedi/drivers/ni_labpc.c b/drivers/staging/comedi/drivers/ni_labpc.c
index 28b91a6..b5a19a0 100644
--- a/drivers/staging/comedi/drivers/ni_labpc.c
+++ b/drivers/staging/comedi/drivers/ni_labpc.c
@@ -772,6 +772,8 @@ void labpc_common_detach(struct comedi_device *dev)
{
struct comedi_subdevice *s;
+ if (!thisboard)
+ return;
if (dev->subdevices) {
s = &dev->subdevices[2];
subdev_8255_cleanup(dev, s);
--
1.7.12
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