staging: comedi: me_daq: fix pointer dereference in me_detach()

As pointed out by Dan Carpenter, dev_private could be NULL when it
is checked before calling comedi_pci_disable(). The private data
variable 'plx_regbase_size' is only used to see if the pci device
has been enabled.

Remove that variable from the private data and just use the unused
dev->iobase variable to let the detach know that the pci device
is enabled.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/drivers/me_daq.c b/drivers/staging/comedi/drivers/me_daq.c
index ddb3dd79874d5aa8e8858dbf8ea36192a27672ae..cdb97955bbc56827331567557550939174fd1854 100644 (file)
--- a/drivers/staging/comedi/drivers/me_daq.c
+++ b/drivers/staging/comedi/drivers/me_daq.c
@@ -224,7 +224,6 @@ static const struct me_board me_boards[] = {
 struct me_private_data {
        void __iomem *plx_regbase;      /* PLX configuration base address */
        void __iomem *me_regbase;       /* Base address of the Meilhaus card */
-       unsigned long plx_regbase_size; /* Size of PLX configuration space */
        unsigned long me_regbase_size;  /* Size of Meilhaus space */
 
        unsigned short control_1;       /* Mirror of CONTROL_1 register */
@@ -639,7 +638,6 @@ static int me_attach_pci(struct comedi_device *dev, struct pci_dev *pcidev)
        struct me_private_data *dev_private;
        struct comedi_subdevice *s;
        resource_size_t plx_regbase_tmp;
-       unsigned long plx_regbase_size_tmp;
        resource_size_t me_regbase_tmp;
        unsigned long me_regbase_size_tmp;
        resource_size_t swap_regbase_tmp;
@@ -664,13 +662,12 @@ static int me_attach_pci(struct comedi_device *dev, struct pci_dev *pcidev)
                        "Failed to enable PCI device and request regions\n");
                return -EIO;
        }
+       dev->iobase = 1;        /* detach needs this */
 
        /* Read PLX register base address [PCI_BASE_ADDRESS #0]. */
        plx_regbase_tmp = pci_resource_start(pcidev, 0);
-       plx_regbase_size_tmp = pci_resource_len(pcidev, 0);
-       dev_private->plx_regbase =
-           ioremap(plx_regbase_tmp, plx_regbase_size_tmp);
-       dev_private->plx_regbase_size = plx_regbase_size_tmp;
+       dev_private->plx_regbase = ioremap(plx_regbase_tmp,
+                                          pci_resource_len(pcidev, 0));
        if (!dev_private->plx_regbase) {
                dev_err(dev->class_dev, "Failed to remap I/O memory\n");
                return -ENOMEM;
@@ -791,7 +788,7 @@ static void me_detach(struct comedi_device *dev)
                        iounmap(dev_private->plx_regbase);
        }
        if (pcidev) {
-               if (dev_private->plx_regbase_size)
+               if (dev->iobase)
                        comedi_pci_disable(pcidev);
                pci_dev_put(pcidev);
        }