usb: hcd: out of bounds access in for_each_companion

commit e86103a75705c7c530768f4ffaba74cf382910f2 upstream.

On BXT platform Host Controller and Device Controller figure as
same PCI device but with different device function. HCD should
not pass data to Device Controller but only to Host Controllers.
Checking if companion device is Host Controller, otherwise skip.

Signed-off-by: Robert Dobrowolski <robert.dobrowolski@linux.intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/usb/core/hcd-pci.c b/drivers/usb/core/hcd-pci.c
index 76be3ba..8312f95 100644 (file)
--- a/drivers/usb/core/hcd-pci.c
+++ b/drivers/usb/core/hcd-pci.c
@@ -70,6 +70,14 @@ static void companion_common(struct pci_dev *pdev, struct usb_hcd *hcd,
                                PCI_SLOT(companion->devfn) != slot)
                        continue;
 
+               /*
+                * Companion device should be either UHCI,OHCI or EHCI host
+                * controller, otherwise skip.
+                */
+               if (companion->class != CL_UHCI && companion->class != CL_OHCI &&
+                               companion->class != CL_EHCI)
+                       continue;
+
                companion_hcd = pci_get_drvdata(companion);
                if (!companion_hcd)
                        continue;