3.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ian Abbott <abbo...@mev.co.uk>
commit 2db012bd40b889d8e5483d3daa07af04c4c109d8 upstream.
`pc236_detach()` is called by the comedi core to clean up if either
`pc236_attach()` or `pc236_attach_pci()` returns an error. It sets
`thisboard` to the return value of `comedi_board(dev)` and assumes it is
non-null. This is a valid assumption if `pc236_attach()` fails, but not
if `pc236_attach_pci()` fails, leading to a possible NULL pointer
dereference.
Check `thisboard` at the top of `pc236_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_pc236.c | 3 +++
1 file changed, 3 insertions(+)
--- a/drivers/staging/comedi/drivers/amplc_pc236.c
+++ b/drivers/staging/comedi/drivers/amplc_pc236.c
@@ -577,8 +577,11 @@ static int __devinit pc236_attach_pci(st
static void pc236_detach(struct comedi_device *dev)
{
+ const struct pc236_board *thisboard = comedi_board(dev);
struct pci_dev *pcidev = comedi_to_pci_dev(dev);
+ if (!thisboard)
+ return;
if (dev->iobase)
pc236_intr_disable(dev);
if (dev->irq)
--
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