3.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ian Abbott <abbo...@mev.co.uk>
commit dfb2540e91e1f63765bc3ff497ad0b714d774261 upstream.
`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.
Signed-off-by: Ian Abbott <abbo...@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
drivers/staging/comedi/drivers/amplc_dio200.c | 2 ++
1 file changed, 2 insertions(+)
--- a/drivers/staging/comedi/drivers/amplc_dio200.c
+++ b/drivers/staging/comedi/drivers/amplc_dio200.c
@@ -1429,6 +1429,8 @@ static void dio200_detach(struct comedi_
const struct dio200_layout_struct *layout;
unsigned n;
+ if (!thisboard)
+ return;
if (dev->irq)
free_irq(dev->irq, dev);
if (dev->subdevices) {
--
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