[PATCH v2 03/11] ShellPkg: acpiview: FADT: Validate global pointer before use

["Krzysztof Koch" <krzysztof.koch@arm.com>]

Check if global pointers have been successfully updated before they
are used for further table parsing.

Signed-off-by: Krzysztof Koch <krzysztof.koch@arm.com>
---

Changes can be seen at: https://github.com/KrzysztofKoch1/edk2/tree/612_add_pointer_validation_v2

Notes:
    v1:
    - Test against NULL pointers [Krzysztof]

    v2:
    - Do not require FadtMinorRevision and X_DsdtAddress pointers to be
      valid in order to process the remaining ACPI tables [Zhichao]

 ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Fadt/FadtParser.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Fadt/FadtParser.c b/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Fadt/FadtParser.c
index e40c9ef8ee4b3285faf8c6edf3cb6236ee367397..6859c4824c2866fd3eb9a789a8dfc950724b27ca 100644
--- a/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Fadt/FadtParser.c
+++ b/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Fadt/FadtParser.c
@@ -204,9 +204,11 @@ ParseAcpiFadt (
     );
 
   if (Trace) {
-    Print (L"\nSummary:\n");
-    PrintFieldName (2, L"FADT Version");
-    Print (L"%d.%d\n",  *AcpiHdrInfo.Revision, *FadtMinorRevision);
+    if (FadtMinorRevision != NULL) {
+      Print (L"\nSummary:\n");
+      PrintFieldName (2, L"FADT Version");
+      Print (L"%d.%d\n",  *AcpiHdrInfo.Revision, *FadtMinorRevision);
+    }
 
     if (*GetAcpiXsdtHeaderInfo ()->OemTableId != *AcpiHdrInfo.OemTableId) {
       IncrementErrorCount ();
@@ -214,21 +216,20 @@ ParseAcpiFadt (
     }
   }
 
-  // If X_DSDT is not zero then use X_DSDT and ignore DSDT,
-  // else use DSDT.
-  if (*X_DsdtAddress != 0) {
+  // If X_DSDT is valid then use X_DSDT and ignore DSDT, else use DSDT.
+  if ((X_DsdtAddress != NULL) && (*X_DsdtAddress != 0)) {
     DsdtPtr = (UINT8*)(UINTN)(*X_DsdtAddress);
-  } else if (*DsdtAddress != 0) {
+  } else if ((DsdtAddress != NULL) && (*DsdtAddress != 0)) {
     DsdtPtr = (UINT8*)(UINTN)(*DsdtAddress);
   } else {
-    // Both DSDT and X_DSDT cannot be zero.
+    // Both DSDT and X_DSDT cannot be invalid.
 #if defined (MDE_CPU_ARM) || defined (MDE_CPU_AARCH64)
     if (Trace) {
       // The DSDT Table is mandatory for ARM systems
       // as the CPU information MUST be presented in
       // the DSDT.
       IncrementErrorCount ();
-      Print (L"ERROR: Both X_DSDT and DSDT are NULL.\n");
+      Print (L"ERROR: Both X_DSDT and DSDT are invalid.\n");
     }
 #endif
     return;
--
'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'