When "reconnect -r" is typed in shell, UsbFreeInterface() is called
to uninstall the UsbIo and DevicePath. But When a UsbIo is opened
by a driver and that driver rejects to close the UsbIo in Stop(),
the uninstall doesn't succeed.
But UsbFreeInterface () frees the DevicePath memory without check
whether the uninstall succeeds.
It leads to the DXE core database contain a DevicePath instance but
that instance's memory is freed.
Assertion happens when someone calls InstallProtocol(DevicePath)
because the InstallProtocol() checks all DevicePath instance to
find whether the same one exits in database.

We haven't seen any USB device driver which rejects to close UsbIo
in Stop(), but it's very likely.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Feng Tian <feng.tian@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
---
 MdeModulePkg/Bus/Usb/UsbBusDxe/UsbEnumer.c | 43 +++++++++++++++++++-----------
 1 file changed, 27 insertions(+), 16 deletions(-)

diff --git a/MdeModulePkg/Bus/Usb/UsbBusDxe/UsbEnumer.c b/MdeModulePkg/Bus/Usb/UsbBusDxe/UsbEnumer.c
index ea54d37c93..b0e6b835ac 100644
--- a/MdeModulePkg/Bus/Usb/UsbBusDxe/UsbEnumer.c
+++ b/MdeModulePkg/Bus/Usb/UsbBusDxe/UsbEnumer.c
@@ -2,7 +2,7 @@
 
     Usb bus enumeration support.
 
-Copyright (c) 2007 - 2014, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2007 - 2017, Intel Corporation. All rights reserved.<BR>
 This program and the accompanying materials
 are licensed and made available under the terms and conditions of the BSD License
 which accompanies this distribution.  The full text of the license may be found at
@@ -53,28 +53,33 @@ UsbGetEndpointDesc (
 
   @param  UsbIf                 The USB interface to free.
 
+  @retval EFI_ACCESS_DENIED     The interface is still occupied.
+  @retval EFI_SUCCESS           The interface is freed.
 **/
-VOID
+EFI_STATUS
 UsbFreeInterface (
   IN USB_INTERFACE        *UsbIf
   )
 {
-  UsbCloseHostProtoByChild (UsbIf->Device->Bus, UsbIf->Handle);
+  EFI_STATUS              Status;
 
-  gBS->UninstallMultipleProtocolInterfaces (
-         UsbIf->Handle,
-         &gEfiDevicePathProtocolGuid,
-         UsbIf->DevicePath,
-         &gEfiUsbIoProtocolGuid,
-         &UsbIf->UsbIo,
-         NULL
-         );
+  UsbCloseHostProtoByChild (UsbIf->Device->Bus, UsbIf->Handle);
 
-  if (UsbIf->DevicePath != NULL) {
-    FreePool (UsbIf->DevicePath);
+  Status = gBS->UninstallMultipleProtocolInterfaces (
+                  UsbIf->Handle,
+                  &gEfiDevicePathProtocolGuid, UsbIf->DevicePath,
+                  &gEfiUsbIoProtocolGuid,      &UsbIf->UsbIo,
+                  NULL
+                  );
+  if (!EFI_ERROR (Status)) {
+    if (UsbIf->DevicePath != NULL) {
+      FreePool (UsbIf->DevicePath);
+    }
+    FreePool (UsbIf);
+  } else {
+    UsbOpenHostProtoByChild (UsbIf->Device->Bus, UsbIf->Handle);
   }
-
-  FreePool (UsbIf);
+  return Status;
 }
 
 
@@ -525,7 +530,13 @@ UsbRemoveConfig (
 
     Status = UsbDisconnectDriver (UsbIf);
     if (!EFI_ERROR (Status)) {
-      UsbFreeInterface (UsbIf);
+      Status = UsbFreeInterface (UsbIf);
+      if (EFI_ERROR (Status)) {
+        UsbConnectDriver (UsbIf);
+      }
+    }
+
+    if (!EFI_ERROR (Status)) {
       Device->Interfaces[Index] = NULL;
     } else {
       ReturnStatus = Status;
-- 
2.12.2.windows.2

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