From d136f0fd47d9953139381c8af74976de86eeb224 Mon Sep 17 00:00:00 2001 From: Ian Abbott Date: Wed, 3 Oct 2012 16:25:20 +0100 Subject: [PATCH] staging: comedi: das08: fix possible NULL deref during detach commit ee280d134f2e05e0172369a53fbe202dbfc527fa upstream. `das08_detach()` is called by the comedi core to clean up if either `das08_attach()` or `das08_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 `das08_attach()` fails, but not if `das08_attach_pci()` fails, leading to a possible NULL pointer dereference. Check `thisboard` at the top of `das08_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/das08.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/staging/comedi/drivers/das08.c b/drivers/staging/comedi/drivers/das08.c index 67a914a10b55..d893e3b20486 100644 --- a/drivers/staging/comedi/drivers/das08.c +++ b/drivers/staging/comedi/drivers/das08.c @@ -1028,6 +1028,8 @@ static void __maybe_unused das08_detach(struct comedi_device *dev) const struct das08_board_struct *thisboard = comedi_board(dev); struct das08_private_struct *devpriv = dev->private; + if (!thisboard) + return; das08_common_detach(dev); if (IS_ENABLED(CONFIG_COMEDI_DAS08_ISA) && (thisboard->bustype == isa || thisboard->bustype == pc104)) { -- 2.39.5