From eb9db72ca867bbe833aaea69178b5a01b686d9bd Mon Sep 17 00:00:00 2001
From: Krzysztof Koch <krzysztof.koch@arm.com>
Date: Mon, 20 Jan 2020 19:13:45 +0800
Subject: ShellPkg: acpiview: SLIT: Validate System Locality count

1. Check if the 'Number of System Localities' provided can be
represented in the SLIT table. The table 'Length' field is a 32-bit
value while the 'Number of System Localities' field is 64-bit long.

2. Check if the SLIT matrix fits in the table buffer. If N is the SLIT
locality count, then the matrix used to represent the localities is
N*N bytes long. The ACPI table length must be big enough to fit the
matrix.

3. Remove (now) redundant 64x64 bit multiplication.

Signed-off-by: Krzysztof Koch <krzysztof.koch@arm.com>
---
 .../Parsers/Slit/SlitParser.c                      | 47 +++++++++++++++++++---
 1 file changed, 42 insertions(+), 5 deletions(-)

(limited to 'ShellPkg/Library')

diff --git a/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Slit/SlitParser.c b/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Slit/SlitParser.c
index 17e2166a09..e4625ee8b1 100644
--- a/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Slit/SlitParser.c
+++ b/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Slit/SlitParser.c
@@ -30,7 +30,7 @@ STATIC CONST ACPI_PARSER SlitParser[] = {
 /**
   Macro to get the value of a System Locality
 **/
-#define SLIT_ELEMENT(Ptr, i, j) *(Ptr + (MultU64x64 (i, LocalityCount)) + j)
+#define SLIT_ELEMENT(Ptr, i, j) *(Ptr + (i * LocalityCount) + j)
 
 /**
   This function parses the ACPI SLIT table.
@@ -57,9 +57,9 @@ ParseAcpiSlit (
   )
 {
   UINT32 Offset;
-  UINT64 Count;
-  UINT64 Index;
-  UINT64 LocalityCount;
+  UINT32 Count;
+  UINT32 Index;
+  UINT32 LocalityCount;
   UINT8* LocalityPtr;
   CHAR16 Buffer[80];  // Used for AsciiName param of ParseAcpi
 
@@ -87,8 +87,45 @@ ParseAcpiSlit (
     return;
   }
 
+  /*
+    Despite the 'Number of System Localities' being a 64-bit field in SLIT,
+    the maximum number of localities that can be represented in SLIT is limited
+    by the 'Length' field of the ACPI table.
+
+    Since the ACPI table length field is 32-bit wide. The maximum number of
+    localities that can be represented in SLIT can be calculated as:
+
+    MaxLocality = sqrt (MAX_UINT32 - sizeof (EFI_ACPI_6_3_SYSTEM_LOCALITY_DISTANCE_INFORMATION_TABLE_HEADER))
+                = 65535
+                = MAX_UINT16
+  */
+  if (*SlitSystemLocalityCount > MAX_UINT16) {
+    IncrementErrorCount ();
+    Print (
+      L"ERROR: The Number of System Localities provided can't be represented " \
+        L"in the SLIT table. SlitSystemLocalityCount = %ld. " \
+        L"MaxLocalityCountAllowed = %d.\n",
+      *SlitSystemLocalityCount,
+      MAX_UINT16
+      );
+    return;
+  }
+
+  LocalityCount = (UINT32)*SlitSystemLocalityCount;
+
+  // Make sure system localities fit in the table buffer provided
+  if (Offset + (LocalityCount * LocalityCount) > AcpiTableLength) {
+    IncrementErrorCount ();
+    Print (
+      L"ERROR: Invalid Number of System Localities. " \
+        L"SlitSystemLocalityCount = %ld. AcpiTableLength = %d.\n",
+      *SlitSystemLocalityCount,
+      AcpiTableLength
+      );
+    return;
+  }
+
   LocalityPtr = Ptr + Offset;
-  LocalityCount = *SlitSystemLocalityCount;
 
   // We only print the Localities if the count is less than 16
   // If the locality count is more than 16 then refer to the
-- 
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