Fix a security hole in shell binaries:

For gBS->LoadImage() if the return status is EFI_SECURITY_VIOLATION, the image handle may not be NULL.
Shell environment should not have the assumption that the output ImageHandle must be NULL if the error status is returned by gBS->LoadImage().

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@9838 6f19259b-4bc3-4df7-8a09-765794883524

EdkShellBinPkg/ReadMe.txt

@@ -1,10 +1,11 @@
-The binaries of EdkShellBinPkg are generated with Efi-Shell-Dev-Snapshot-20091214.zip and build with Edk Compatibility & BaseTools Package
+The binaries of EdkShellBinPkg are generated with Efi-Shell-Dev-Snapshot-20091214.zip (plus a security hot-fix see EdkShellbinPkg\SecurityPatch.diff) and build with Edk Compatibility & BaseTools Package
 (r9623)
 
 The following steps can help to re-generate these binaries for customization:
 1. Check out EdkCompatibilityPkg (r9623) to $(WORKSPACE)\EdkCompatibilityPkg (svn https://edk2.tianocore.org/svn/edk2/trunk/edk2/EdkCompatibilityPkg).
 2. Check out EdkShellPkg(r9623) to $(WORKSPACE)\EdkShellPkg (svn https://edk2.tianocore.org/svn/edk2/trunk/edk2/EdkShellPkg).
-3  Check out Edk Shell project source (r36) to $(WORKSPACE) (svn https://efi-shell.tianocore.org/svn/efi-shell/trunk/Shell).  It is read-only and current revison (r36) is identical to Efi-Shell-Dev-Snapshot-20091214.zip. 
+3a.Check out Edk Shell project source (r36) to $(WORKSPACE) (svn https://efi-shell.tianocore.org/svn/efi-shell/trunk/Shell).  It is read-only and current revison (r36) is identical to Efi-Shell-Dev-Snapshot-20091214.zip. 
+3b.Apply the security hot fix in EdkShellBinPkg\SecurityPatch.diff to patch in Shell\shellenv\exec.c
 4. Update to the newest BaseTools package. (r9623 or later)
 5. Under workspace directory (i.e. c:\EdkII), 
    To generate Minimum Shell, execute: "build -a IA32 -a X64 -a IPF -p EdkShellPkg\EdkShellPkg.dsc -m EdkShellPkg\Shell\Shell.inf" 

EdkShellBinPkg/SecurityPatch.diff

@@ -0,0 +1,15 @@
+Index: shellenv/exec.c
+===================================================================
+--- shellenv/exec.c	(revision 36)
++++ shellenv/exec.c	(working copy)
+@@ -2079,6 +2079,10 @@
+         if (!EFI_ERROR (Status)) {
+           goto Done;
+         } else {
++          //
++          // Set ImageHandle to NULL if any error status is returned.
++          //
++          ImageHandle = NULL;
+           Status = LibGetImageHeader (
+                      DevicePath,
+                      &DosHeader,