[PATCH v3 02/11] ShellPkg: acpiview: RSDP: Validate global pointer before use

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

Check if XsdtAddress pointer has been successfully updated before it
is used for further table parsing.

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

Notes:
    v3:
    - Rebase on latest master [Krzysztof]

    v1:
    - Test against NULL pointers [Krzysztof]

 ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Rsdp/RsdpParser.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Rsdp/RsdpParser.c b/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Rsdp/RsdpParser.c
index 5a5c4b50c12e6eb0aa0efb1765df7e123f614da3..f4a8732a7db7c437031f2a3d2f266b80eff17b4b 100644
--- a/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Rsdp/RsdpParser.c
+++ b/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Rsdp/RsdpParser.c
@@ -138,6 +138,18 @@ ParseAcpiRsdp (
     PARSER_PARAMS (RsdpParser)
     );
 
+  // Check if the values used to control the parsing logic have been
+  // successfully read.
+  if (XsdtAddress == NULL) {
+    IncrementErrorCount ();
+    Print (
+      L"ERROR: Insufficient table length. AcpiTableLength = %d." \
+        L"RSDP parsing aborted.\n",
+      AcpiTableLength
+      );
+    return;
+  }
+
   // This code currently supports parsing of XSDT table only
   // and does not parse the RSDT table. Platforms provide the
   // RSDT to enable compatibility with ACPI 1.0 operating systems.
--
'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'