From 6c04efd97dd25596a1bf80cc1c518fe7e451cc1e Mon Sep 17 00:00:00 2001 From: Ian Abbott Date: Wed, 3 Oct 2012 16:25:18 +0100 Subject: [PATCH] staging: comedi: amplc_pc236: fix possible NULL deref during detach 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 Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/drivers/amplc_pc236.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/staging/comedi/drivers/amplc_pc236.c b/drivers/staging/comedi/drivers/amplc_pc236.c index cfbb83b9526a..b46e66310d71 100644 --- 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(struct comedi_device *dev, 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) -- 2.39.5