1 files changed, 18 insertions, 4 deletions

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 06e7023258d0..e5a01713f937 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -1401,6 +1401,7 @@ int xhci_add_endpoint(struct usb_hcd *hcd, struct usb_device *udev,
         u32 added_ctxs;
         unsigned int last_ctx;
         u32 new_add_flags, new_drop_flags, new_slot_info;
+        struct xhci_virt_device *virt_dev;
         int ret = 0;
 
         ret = xhci_check_args(hcd, udev, ep, 1, true, __func__);
@@ -1425,11 +1426,25 @@ int xhci_add_endpoint(struct usb_hcd *hcd, struct usb_device *udev,
                 return 0;
         }
 
-        in_ctx = xhci->devs[udev->slot_id]->in_ctx;
-        out_ctx = xhci->devs[udev->slot_id]->out_ctx;
+        virt_dev = xhci->devs[udev->slot_id];
+        in_ctx = virt_dev->in_ctx;
+        out_ctx = virt_dev->out_ctx;
         ctrl_ctx = xhci_get_input_control_ctx(xhci, in_ctx);
         ep_index = xhci_get_endpoint_index(&ep->desc);
         ep_ctx = xhci_get_ep_ctx(xhci, out_ctx, ep_index);
+
+        /* If this endpoint is already in use, and the upper layers are trying
+         * to add it again without dropping it, reject the addition.
+         */
+        if (virt_dev->eps[ep_index].ring &&
+                        !(le32_to_cpu(ctrl_ctx->drop_flags) &
+                                xhci_get_endpoint_flag(&ep->desc))) {
+                xhci_warn(xhci, "Trying to add endpoint 0x%x "
+                                "without dropping it.\n",
+                                (unsigned int) ep->desc.bEndpointAddress);
+                return -EINVAL;
+        }
+
         /* If the HCD has already noted the endpoint is enabled,
          * ignore this request.
          */
@@ -1445,8 +1460,7 @@ int xhci_add_endpoint(struct usb_hcd *hcd, struct usb_device *udev,
          * process context, not interrupt context (or so documenation
          * for usb_set_interface() and usb_set_configuration() claim).
          */
-        if (xhci_endpoint_init(xhci, xhci->devs[udev->slot_id],
-                                udev, ep, GFP_NOIO) < 0) {
+        if (xhci_endpoint_init(xhci, virt_dev, udev, ep, GFP_NOIO) < 0) {
                 dev_dbg(&udev->dev, "%s - could not initialize ep %#x\n",
                                 __func__, ep->desc.bEndpointAddress);
                 return -ENOMEM;