File CVE-2017-5973-qemuu-usb-infinite-loop-while-doing-control-transfer-in-xhci_kick_epctx.patch of Package xen.11298

References: bsc#1025188 CVE-2017-5973

Limits should be big enough that normal guest should not hit it.
Add a tracepoint to log them, just in case.  Also, while being
at it, log the existing link trb limit too.

Reported-by: 李强 <address@hidden>
Signed-off-by: Gerd Hoffmann <address@hidden>
---
 hw/usb/hcd-xhci.c   | 15 ++++++++++++++-
 hw/usb/trace-events |  1 +
 2 files changed, 15 insertions(+), 1 deletion(-)

Index: xen-4.5.5-testing/tools/qemu-xen-dir-remote/hw/usb/hcd-xhci.c
===================================================================
--- xen-4.5.5-testing.orig/tools/qemu-xen-dir-remote/hw/usb/hcd-xhci.c
+++ xen-4.5.5-testing/tools/qemu-xen-dir-remote/hw/usb/hcd-xhci.c
@@ -53,6 +53,8 @@
 #define ER_FULL_HACK
 
 #define TRB_LINK_LIMIT  4
+#define COMMAND_LIMIT   256
+#define TRANSFER_LIMIT  256
 
 #define LEN_CAP         0x40
 #define LEN_OPER        (0x400 + 0x10 * MAXPORTS)
@@ -1009,6 +1011,7 @@ static TRBType xhci_ring_fetch(XHCIState
             return type;
         } else {
             if (++link_cnt > TRB_LINK_LIMIT) {
+                trace_usb_xhci_enforced_limit("trb-link");
                 return 0;
             }
             ring->dequeue = xhci_mask64(trb->parameter);
@@ -2078,6 +2081,7 @@ static void xhci_kick_ep(XHCIState *xhci
     XHCIRing *ring;
     USBEndpoint *ep = NULL;
     uint64_t mfindex;
+    unsigned int count = 0;
     int length;
     int i;
 
@@ -2216,6 +2220,10 @@ static void xhci_kick_ep(XHCIState *xhci
             epctx->retry = xfer;
             break;
         }
+        if (count++ > TRANSFER_LIMIT) {
+            trace_usb_xhci_enforced_limit("transfers");
+            break;
+        }
     }
 
     ep = xhci_epid_to_usbep(xhci, slotid, epid);
@@ -2683,7 +2691,7 @@ static void xhci_process_commands(XHCISt
     TRBType type;
     XHCIEvent event = {ER_COMMAND_COMPLETE, CC_SUCCESS};
     dma_addr_t addr;
-    unsigned int i, slotid = 0;
+    unsigned int i, slotid = 0, count = 0;
 
     DPRINTF("xhci_process_commands()\n");
     if (!xhci_running(xhci)) {
@@ -2797,6 +2805,11 @@ static void xhci_process_commands(XHCISt
         }
         event.slotid = slotid;
         xhci_event(xhci, &event, 0);
+
+        if (count++ > COMMAND_LIMIT) {
+            trace_usb_xhci_enforced_limit("commands");
+            return;
+        }
     }
 }
 
Index: xen-4.5.5-testing/tools/qemu-xen-dir-remote/trace-events
===================================================================
--- xen-4.5.5-testing.orig/tools/qemu-xen-dir-remote/trace-events
+++ xen-4.5.5-testing/tools/qemu-xen-dir-remote/trace-events
@@ -394,6 +394,7 @@ usb_xhci_xfer_retry(void *xfer) "%p"
 usb_xhci_xfer_success(void *xfer, uint32_t bytes) "%p: len %d"
 usb_xhci_xfer_error(void *xfer, uint32_t ret) "%p: ret %d"
 usb_xhci_unimplemented(const char *item, int nr) "%s (0x%x)"
+usb_xhci_enforced_limit(const char *item) "%s"
 
 # hw/usb/desc.c
 usb_desc_device(int addr, int len, int ret) "dev %d query device, len %d, ret %d"