MdePkg: Additional CodeQL fixes (#266)

## Description

Fixes for additional CodeQL queries.

- [x] Impacts functionality?
  - **Functionality** - Does the change ultimately impact how firmware functions?
  - Examples: Add a new library, publish a new PPI, update an algorithm, ...
- [x] Impacts security?
  - **Security** - Does the change have a direct security impact on an application,
    flow, or firmware?
  - Examples: Crypto algorithm change, buffer overflow fix, parameter
    validation improvement, ...
- [ ] Breaking change?
  - **Breaking change** - Will anyone consuming this change experience a break
    in build or boot behavior?
  - Examples: Add a new library class, move a module to a different repo, call
    a function in a new library class in a pre-existing module, ...
- [ ] Includes tests?
  - **Tests** - Does the change include any explicit test code?
  - Examples: Unit tests, integration tests, robot tests, ...
- [ ] Includes documentation?
  - **Documentation** - Does the change contain explicit documentation additions
    outside direct code modifications (and comments)?
  - Examples: Update readme file, add feature readme file, link to documentation
    on an a separate Web page, ...

## How This Was Tested

Build MdePkg and boot changes on QemuQ35Pkg to EFI shell.

## Integration Instructions

N/A

Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>

MdePkg/Library/BasePeCoffLib/BasePeCoff.c

@@ -1576,11 +1576,8 @@ PeCoffLoaderLoadImage (
       return RETURN_LOAD_ERROR;
     }
 
-    if ((Base == NULL) || (End == NULL)) {
-      DEBUG ((DEBUG_WARN | DEBUG_LOAD, "%a PeCoffLoaderImageAddress resolved NULL for Base (0x%p) or End (0x%p)\n", __FUNCTION__, Base, End));
-    }
-
-    if (Section->SizeOfRawData > 0) {
+    // MU_CHANGE - CodeQL change
+    if ((Section->SizeOfRawData > 0) && (Base != NULL)) {
       Status = ImageContext->ImageRead (
                                ImageContext->Handle,
                                Section->PointerToRawData - TeStrippedOffset,
@@ -1596,8 +1593,8 @@ PeCoffLoaderLoadImage (
     //
     // If raw size is less then virtual size, zero fill the remaining
     //
-
-    if (Size < Section->Misc.VirtualSize) {
+    // MU_CHANGE - CodeQL change - Assume Base is non-NULL if Size is non-zero
+    if ((Size < Section->Misc.VirtualSize) && (Base != NULL)) {
       ZeroMem (Base + Size, Section->Misc.VirtualSize - Size);
     }
 

MdePkg/Library/UefiPciSegmentLibPciRootBridgeIo/PciSegmentLib.c

@@ -184,7 +184,13 @@ DxePciSegmentLibPciRootBridgeIoReadWorker (
   EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL  *PciRootBridgeIo;
 
   PciRootBridgeIo = PciSegmentLibSearchForRootBridge (Address);
-  ASSERT (PciRootBridgeIo != NULL);
+  // MU_CHANGE [BEGIN] - CodeQL change
+  if (PciRootBridgeIo == NULL) {
+    ASSERT (PciRootBridgeIo != NULL);
+    return 0;
+  }
+
+  // MU_CHANGE [END] - CodeQL change
 
   PciRootBridgeIo->Pci.Read (
                          PciRootBridgeIo,
@@ -223,7 +229,13 @@ DxePciSegmentLibPciRootBridgeIoWriteWorker (
   EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL  *PciRootBridgeIo;
 
   PciRootBridgeIo = PciSegmentLibSearchForRootBridge (Address);
-  ASSERT (PciRootBridgeIo != NULL);
+  // MU_CHANGE [BEGIN] - CodeQL change
+  if (PciRootBridgeIo == NULL) {
+    ASSERT (PciRootBridgeIo != NULL);
+    return 0;
+  }
+
+  // MU_CHANGE [END] - CodeQL change
 
   PciRootBridgeIo->Pci.Write (
                          PciRootBridgeIo,