From dfb2540e91e1f63765bc3ff497ad0b714d774261 Mon Sep 17 00:00:00 2001 From: Ian Abbott Date: Wed, 3 Oct 2012 16:25:16 +0100 Subject: [PATCH] staging: comedi: amplc_dio200: fix possible NULL deref during detach `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: # 3.6.x Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- 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 08f305210a6..29eb52d11d2 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) { -- 2.41.0