MdeModulePkg/CapsuleApp: Fix potential NULL pointer dereference issue

To avoid potential NULL pointer dereference issue. Initialize them at
the beginning of the function.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao Wu <hao.a.wu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Chen A Chen <chen.a.chen@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

MdeModulePkg/Application/CapsuleApp/CapsuleApp.c

@@ -916,6 +916,7 @@ UefiMain (
   EFI_GUID                      ImageTypeId;
   UINTN                         ImageIndex;
 
+  BlockDescriptors  = NULL;
   MapFsStr          = NULL;
   CapsuleNum        = 0;
 

MdeModulePkg/Application/CapsuleApp/CapsuleDump.c

@@ -798,6 +798,8 @@ DumpCapsuleFromDisk (
   DirHandle       = NULL;
   FileHandle      = NULL;
   Index           = 0;
+  FileInfoBuffer  = NULL;
+  FileInfo        = NULL;
   FileCount       = 0;
   NoFile          = FALSE;
 
@@ -971,6 +973,9 @@ DumpProvisionedCapsule (
   ShellProtocol = GetShellProtocol ();
 
   Index             = 0;
+  CapsuleDataPtr64  = NULL;
+  BootNext          = NULL;
+  ShellProtocol     = NULL;
 
   //
   // Dump capsule provisioned on Memory

MdeModulePkg/Application/CapsuleApp/CapsuleOnDisk.c

@@ -151,9 +151,14 @@ DumpAllEfiSysPartition (
   UINTN                      NumberEfiSystemPartitions;
   EFI_SHELL_PROTOCOL         *ShellProtocol;
 
-  ShellProtocol = GetShellProtocol ();
   NumberEfiSystemPartitions = 0;
 
+  ShellProtocol = GetShellProtocol ();
+  if (ShellProtocol == NULL) {
+    Print (L"Get Shell Protocol Fail\n");;
+    return ;
+  }
+
   Print (L"EFI System Partition list:\n");
 
   gBS->LocateHandleBuffer (
@@ -421,7 +426,13 @@ GetUpdateFileSystem (
   EFI_BOOT_MANAGER_LOAD_OPTION    NewOption;
 
   MappedDevicePath = NULL;
+  BootOptionBuffer = NULL;
+
   ShellProtocol = GetShellProtocol ();
+  if (ShellProtocol == NULL) {
+    Print (L"Get Shell Protocol Fail\n");;
+    return EFI_NOT_FOUND;
+  }
 
   //
   // 1. If Fs is not assigned and there are capsule provisioned before,
@@ -468,7 +479,9 @@ GetUpdateFileSystem (
   // 2. Get EFI system partition form boot options.
   //
   BootOptionBuffer = EfiBootManagerGetLoadOptions (&BootOptionCount, LoadOptionTypeBoot);
-  if (BootOptionCount == 0 && Map == NULL) {
+  if ( (BootOptionBuffer == NULL) ||
+       (BootOptionCount == 0 && Map == NULL)
+     ) {
     return EFI_NOT_FOUND;
   }