error handling enhancement for possible null pointer dereference

Signed-off-by: erictian
Reviewed-by: ydong10

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12437 6f19259b-4bc3-4df7-8a09-765794883524

MdeModulePkg/Bus/Usb/UsbBusPei/UsbPeim.c

@@ -1,7 +1,7 @@
 /** @file
 The module to produce Usb Bus PPI.
 
-Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>
   
 This program and the accompanying materials
 are licensed and made available under the terms and conditions
@@ -380,18 +380,21 @@ PeiUsbEnumeration (
 
 
   CurrentAddress = 0;
-  if (Usb2HcPpi != NULL){
+  if (Usb2HcPpi != NULL) {
     Usb2HcPpi->GetRootHubPortNumber (
                 PeiServices,
                 Usb2HcPpi,
                 (UINT8 *) &NumOfRootPort
                 );    
-  } else {
+  } else if (UsbHcPpi != NULL) {
     UsbHcPpi->GetRootHubPortNumber (
                 PeiServices,
                 UsbHcPpi,
                 (UINT8 *) &NumOfRootPort
                 );
+  } else {
+    ASSERT (FALSE);
+    return EFI_INVALID_PARAMETER;
   }
 
   for (Index = 0; Index < NumOfRootPort; Index++) {

MdeModulePkg/Bus/Usb/UsbKbDxe/KeyBoard.c

@@ -627,13 +627,18 @@ SetKeyboardLayoutEvent (
     //
     KeyCode = EfiKeyToUsbKeyCodeConvertionTable [(UINT8) (TempKey.Key)];
     TableEntry = GetKeyDescriptor (UsbKeyboardDevice, KeyCode);
+    if (TableEntry == NULL) {
+      ReleaseKeyboardLayoutResources (UsbKeyboardDevice);
+      FreePool (KeyboardLayout);
+      return;
+    }
     CopyMem (TableEntry, KeyDescriptor, sizeof (EFI_KEY_DESCRIPTOR));
 
     //
     // For non-spacing key, create the list with a non-spacing key followed by physical keys.
     //
     if (TempKey.Modifier == EFI_NS_KEY_MODIFIER) {
-      UsbNsKey = AllocatePool (sizeof (USB_NS_KEY));
+      UsbNsKey = AllocateZeroPool (sizeof (USB_NS_KEY));
       ASSERT (UsbNsKey != NULL);
 
       //