commit: 1d1171ffda585c1cab7bd7cf4bd8f8fd5923fb4a
From: Ian Abbott <[email protected]>
Date: Wed, 3 Oct 2012 16:25:19 +0100
Subject: staging: comedi: amplc_pc263: fix possible NULL deref during detach

`pc263_detach()` is called by the comedi core to clean up if either
`pc263_attach()` or `pc263_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 `pc263_attach()` fails, but not
if `pc263_attach_pci()` fails, leading to a possible NULL pointer
dereference.

Check `thisboard` at the top of `pc263_detach()` and return early if it
is `NULL`.  This is okay because no other resources need cleaning up in
this case.

Cc: <[email protected]> # 3.6.x
Signed-off-by: Ian Abbott <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 drivers/staging/comedi/drivers/amplc_pc263.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/staging/comedi/drivers/amplc_pc263.c 
b/drivers/staging/comedi/drivers/amplc_pc263.c
index 60830cc..d0a4c44 100644
--- a/drivers/staging/comedi/drivers/amplc_pc263.c
+++ b/drivers/staging/comedi/drivers/amplc_pc263.c
@@ -323,6 +323,8 @@ static void pc263_detach(struct comedi_device *dev)
 {
        const struct pc263_board *thisboard = comedi_board(dev);
 
+       if (!thisboard)
+               return;
        if (is_isa_board(thisboard)) {
                if (dev->iobase)
                        release_region(dev->iobase, PC263_IO_SIZE);
-- 
1.7.3.4
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