xen-pciback: fix up cleanup path when alloc fails

When allocating a pciback device fails, clear the private
field. This could lead to an use-after free, however
the 'really_probe' takes care of setting
dev_set_drvdata(dev, NULL) in its failure path (which we would
exercise if the ->probe function failed), so we we
are OK. However lets be defensive as the code can change.

Going forward we should clean up the pci_set_drvdata(dev, NULL)
in the various code-base. That will be for another day.

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reported-by: Jonathan Creekmore <jonathan.creekmore@gmail.com>
Signed-off-by: Doug Goldstein <cardoe@cardoe.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
(cherry picked from commit 584a561a6fee0d258f9ca644f58b73d9a41b8a46)
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>

diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
index 98bc345f296ef866eaf0e3b1ffffad12ca35fb7e..4843741e703a336da72162af91165392f0560490 100644 (file)
--- a/drivers/xen/xen-pciback/xenbus.c
+++ b/drivers/xen/xen-pciback/xenbus.c
@@ -44,7 +44,6 @@ static struct xen_pcibk_device *alloc_pdev(struct xenbus_device *xdev)
        dev_dbg(&xdev->dev, "allocated pdev @ 0x%p\n", pdev);
 
        pdev->xdev = xdev;
-       dev_set_drvdata(&xdev->dev, pdev);
 
        mutex_init(&pdev->dev_lock);
 
@@ -58,6 +57,9 @@ static struct xen_pcibk_device *alloc_pdev(struct xenbus_device *xdev)
                kfree(pdev);
                pdev = NULL;
        }
+
+       dev_set_drvdata(&xdev->dev, pdev);
+
 out:
        return pdev;
 }