diff --git a/hw/usb/hcd-ohci.c b/hw/usb/hcd-ohci.c
index 1e6e85e86a..9dc59101f9 100644
--- a/hw/usb/hcd-ohci.c
+++ b/hw/usb/hcd-ohci.c
@@ -731,7 +731,11 @@ static int ohci_service_iso_td(OHCIState *ohci, struct ohci_ed *ed,
     }
 
     start_offset = iso_td.offset[relative_frame_number];
-    next_offset = iso_td.offset[relative_frame_number + 1];
+    if (relative_frame_number < frame_count) {
+        next_offset = iso_td.offset[relative_frame_number + 1];
+    } else {
+        next_offset = iso_td.be;
+    }
 
     if (!(OHCI_BM(start_offset, TD_PSW_CC) & 0xe) || 
         ((relative_frame_number < frame_count) && 
@@ -764,7 +768,12 @@ static int ohci_service_iso_td(OHCIState *ohci, struct ohci_ed *ed,
         }
     } else {
         /* Last packet in the ISO TD */
-        end_addr = iso_td.be;
+        end_addr = next_offset;
+    }
+
+    if (start_addr > end_addr) {
+        trace_usb_ohci_iso_td_bad_cc_overrun(start_addr, end_addr);
+        return 1;
     }
 
     if ((start_addr & OHCI_PAGE_MASK) != (end_addr & OHCI_PAGE_MASK)) {
@@ -773,6 +782,9 @@ static int ohci_service_iso_td(OHCIState *ohci, struct ohci_ed *ed,
     } else {
         len = end_addr - start_addr + 1;
     }
+    if (len > sizeof(ohci->usb_buf)) {
+        len = sizeof(ohci->usb_buf);
+    }
 
     if (len && dir != OHCI_TD_DIR_IN) {
         if (ohci_copy_iso_td(ohci, start_addr, end_addr, ohci->usb_buf, len,
@@ -975,8 +987,16 @@ static int ohci_service_td(OHCIState *ohci, struct ohci_ed *ed)
         if ((td.cbp & 0xfffff000) != (td.be & 0xfffff000)) {
             len = (td.be & 0xfff) + 0x1001 - (td.cbp & 0xfff);
         } else {
+            if (td.cbp > td.be) {
+                trace_usb_ohci_iso_td_bad_cc_overrun(td.cbp, td.be);
+                ohci_die(ohci);
+                return 1;
+            }
             len = (td.be - td.cbp) + 1;
         }
+        if (len > sizeof(ohci->usb_buf)) {
+            len = sizeof(ohci->usb_buf);
+        }
 
         pktlen = len;
         if (len && dir != OHCI_TD_DIR_IN) {