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Commit d30b2a20 authored by Sarah Sharp's avatar Sarah Sharp
Browse files

xhci: Limit roothub ports to 15 USB3 & 31 USB2 ports. 



The USB core allocates a USB 2.0 roothub descriptor that has room for 31
(USB_MAXCHILDREN) ports' worth of DeviceRemovable and PortPwrCtrlMask
fields.  Limit the number of USB 2.0 roothub ports accordingly.  I don't
expect to run into this limitation ever, but this prevents a buffer
overflow issue in the roothub descriptor filling code.

Similarly, a USB 3.0 hub can only have 15 downstream ports, so limit the
USB 3.0 roothub to 15 USB 3.0 ports.

Signed-off-by: default avatarSarah Sharp <sarah.a.sharp@linux.intel.com>
parent 4bbb0ace

drivers/usb/host/xhci-mem.c

+18 −0
Original line number Diff line number Diff line
@@ -1803,6 +1803,20 @@ static int xhci_setup_port_arrays(struct xhci_hcd *xhci, gfp_t flags) 
	}

	xhci_dbg(xhci, "Found %u USB 2.0 ports and %u USB 3.0 ports.\n",

			xhci->num_usb2_ports, xhci->num_usb3_ports);



	/* Place limits on the number of roothub ports so that the hub

	 * descriptors aren't longer than the USB core will allocate.

	 */

	if (xhci->num_usb3_ports > 15) {

		xhci_dbg(xhci, "Limiting USB 3.0 roothub ports to 15.\n");

		xhci->num_usb3_ports = 15;

	}

	if (xhci->num_usb2_ports > USB_MAXCHILDREN) {

		xhci_dbg(xhci, "Limiting USB 2.0 roothub ports to %u.\n",

				USB_MAXCHILDREN);

		xhci->num_usb2_ports = USB_MAXCHILDREN;

	}



	/*

	 * Note we could have all USB 3.0 ports, or all USB 2.0 ports.

	 * Not sure how the USB core will handle a hub with no ports...
@@ -1827,6 +1841,8 @@ static int xhci_setup_port_arrays(struct xhci_hcd *xhci, gfp_t flags) 
					"addr = %p\n", i,

					xhci->usb2_ports[port_index]);

			port_index++;

			if (port_index == xhci->num_usb2_ports)

				break;

		}

	}

	if (xhci->num_usb3_ports) {
@@ -1845,6 +1861,8 @@ static int xhci_setup_port_arrays(struct xhci_hcd *xhci, gfp_t flags) 
						"addr = %p\n", i,

						xhci->usb3_ports[port_index]);

				port_index++;

				if (port_index == xhci->num_usb3_ports)

					break;

			}

	}

	return 0;