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: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>
---
drivers/usb/host/xhci-mem.c | 18 ++++++++++++++++++
1 files changed, 18 insertions(+), 0 deletions(-)
diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 8e5f0c3..6bcfc13 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -1774,6 +1774,20 @@ 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...
@@ -1794,6 +1808,8 @@ 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) {
@@ -1812,6 +1828,8 @@ 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;
--
1.6.3.3
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