[Qemu-devel] [PATCH] usb/ohci: Fix crash with when specifying too many num-ports

[Qemu-devel] [PATCH] usb/ohci: Fix crash with when specifying too many num-ports

[Thomas Huth]

QEMU currently crashes when an OHCI controller is instantiated with
too many ports, e.g. "-device pci-ohci,num-ports=100,masterbus=1".
Thus add a proper check in usb_ohci_init() to make sure that we
do not use more than OHCI_MAX_PORTS = 15 ports here.

Ticket: https://bugs.launchpad.net/qemu/+bug/1581308
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 hw/usb/hcd-ohci.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/hw/usb/hcd-ohci.c b/hw/usb/hcd-ohci.c
index ffab561..16d9ff7 100644
--- a/hw/usb/hcd-ohci.c
+++ b/hw/usb/hcd-ohci.c
@@ -1848,6 +1848,12 @@ static void usb_ohci_init(OHCIState *ohci, DeviceState *dev,
 
     ohci->as = as;
 
+    if (num_ports > OHCI_MAX_PORTS) {
+        error_setg(errp, "OHCI num-ports=%d is too big (limit is %d ports)",
+                   num_ports, OHCI_MAX_PORTS);
+        return;
+    }
+
     if (usb_frame_time == 0) {
 #ifdef OHCI_TIME_WARP
         usb_frame_time = NANOSECONDS_PER_SECOND;
-- 
1.8.3.1