--- /dev/null
+From 95ed56939eb2eaa4e2f349fe6dcd13ca4edfd8fb Mon Sep 17 00:00:00 2001
+From: Li Qiang <liqiang6-s@360.cn>
+Date: Tue, 7 Feb 2017 02:23:33 -0800
+Subject: [PATCH] usb: ohci: limit the number of link eds
+
+The guest may builds an infinite loop with link eds. This patch
+limit the number of linked ed to avoid this.
+
+Signed-off-by: Li Qiang <liqiang6-s@360.cn>
+Message-id: 5899a02e.45ca240a.6c373.93c1@mx.google.com
+Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
+---
+ hw/usb/hcd-ohci.c | 9 ++++++++-
+ 1 file changed, 8 insertions(+), 1 deletion(-)
+
+diff --git a/hw/usb/hcd-ohci.c b/hw/usb/hcd-ohci.c
+index 2cba3e3..21c93e0 100644
+--- a/hw/usb/hcd-ohci.c
++++ b/hw/usb/hcd-ohci.c
+@@ -42,6 +42,8 @@
+
+ #define OHCI_MAX_PORTS 15
+
++#define ED_LINK_LIMIT 4
++
+ static int64_t usb_frame_time;
+ static int64_t usb_bit_time;
+
+@@ -1184,7 +1186,7 @@ static int ohci_service_ed_list(OHCIState *ohci, uint32_t head, int completion)
+ uint32_t next_ed;
+ uint32_t cur;
+ int active;
+-
++ uint32_t link_cnt = 0;
+ active = 0;
+
+ if (head == 0)
+@@ -1199,6 +1201,11 @@ static int ohci_service_ed_list(OHCIState *ohci, uint32_t head, int completion)
+
+ next_ed = ed.next & OHCI_DPTR_MASK;
+
++ if (++link_cnt > ED_LINK_LIMIT) {
++ ohci_die(ohci);
++ return 0;
++ }
++
+ if ((ed.head & OHCI_ED_H) || (ed.flags & OHCI_ED_K)) {
+ uint32_t addr;
+ /* Cancel pending packets for ED that have been paused. */
+--
+2.10.2
+