[PATCH 4.2.y-ckt 50/93] usb: hcd: out of bounds access in for_each_companion

[Kamal Mostafa]

4.2.8-ckt9 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Robert Dobrowolski <robert.dobrowolski at linux.intel.com>

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 at linux.intel.com>
Acked-by: Alan Stern <stern at rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/usb/core/hcd-pci.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/usb/core/hcd-pci.c b/drivers/usb/core/hcd-pci.c
index 9eb1cff..b8b580e 100644
--- a/drivers/usb/core/hcd-pci.c
+++ b/drivers/usb/core/hcd-pci.c
@@ -74,6 +74,15 @@ static void for_each_companion(struct pci_dev *pdev, struct usb_hcd *hcd,
 		if (companion->bus != pdev->bus ||
 				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 || !companion_hcd->self.root_hub)
 			continue;
-- 
2.7.4