[PATCH 3.12 04/76] usb: hcd: out of bounds access in for_each_companion

[Jiri Slaby]

From: Robert Dobrowolski <robert.dobrowolski@xxxxxxxxxxxxxxx>

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

===============

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: Jiri Slaby <jslaby@xxxxxxx>
---
 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 04b21577e8ed..1778aeeb9e5c 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;
-- 
2.8.2