[PATCH 3.16 023/114] usb: hcd: out of bounds access in for_each_companion

[Ben Hutchings]

3.16.36-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Robert Dobrowolski <robert.dobrowolski@xxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxx>
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/usb/core/hcd-pci.c | 9 +++++++++
 1 file changed, 9 insertions(+)

--- a/drivers/usb/core/hcd-pci.c
+++ b/drivers/usb/core/hcd-pci.c
@@ -74,6 +74,15 @@ static void for_each_companion(struct pc
 		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;