staging: comedi: amplc_pc236: fix invalid register access during detach

commit aaeb61a97b upstream.

`pc236_detach()` is called by the comedi core if it attempted to attach
a device and failed.  `pc236_detach()` calls `pc236_intr_disable()` if
the comedi device private data pointer (`devpriv`) is non-null.  This
test is insufficient as `pc236_intr_disable()` accesses hardware
registers and the attach routine may have failed before it has saved
their I/O base addresses.

Fix it by checking `dev->iobase` is non-zero before calling
`pc236_intr_disable()` as that means the I/O base addresses have been
saved and the hardware registers can be accessed.  It also implies the
comedi device private data pointer is valid, so there is no need to
check it.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ian Abbott 2012-10-03 16:25:17 +01:00 committed by Greg Kroah-Hartman
parent 775dc1a3fd
commit a0419caba8

View file

@ -468,7 +468,7 @@ static int pc236_detach(struct comedi_device *dev)
{
printk(KERN_DEBUG "comedi%d: %s: detach\n", dev->minor,
PC236_DRIVER_NAME);
if (devpriv)
if (dev->iobase)
pc236_intr_disable(dev);
if (dev->irq)