From 58cc0ffe68e249ffcc73ee3d8e2120be27793f28 Mon Sep 17 00:00:00 2001
From: Krzysztof Koch <krzysztof.koch@arm.com>
Date: Mon, 22 Jul 2019 15:50:21 -0700
Subject: [PATCH] ShellPkg: acpiview: Allow passing buffer length to
 DumpGasStruct()

Modify the signature of the DumpGasStruct() function to include the
buffer length parameter and to return the number of bytes parsed by
the function.

This way it becomes possible to prevent buffer overruns when dumping
Generic Address Structure's (GAS) fields in the acpiview table
parsers.

Update all existing DumpGasStruct() calls in acpiview to add the
length argument.

Signed-off-by: Krzysztof Koch <krzysztof.koch@arm.com>
Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>
Reviewed-by: Zhichao Gao <zhichao.gao@intel.com>
---
 .../UefiShellAcpiViewCommandLib/AcpiParser.c  | 26 +++++++++++--------
 .../UefiShellAcpiViewCommandLib/AcpiParser.h  |  8 ++++--
 .../Parsers/Dbg2/Dbg2Parser.c                 |  2 +-
 3 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.c b/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.c
index 8b3153516d..2d6ff80e29 100644
--- a/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.c
+++ b/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.c
@@ -589,23 +589,27 @@ STATIC CONST ACPI_PARSER GasParser[] = {
 
   @param [in] Ptr     Pointer to the start of the buffer.
   @param [in] Indent  Number of spaces to indent the output.
+  @param [in] Length  Length of the GAS structure buffer.
+
+  @retval Number of bytes parsed.
 **/
-VOID
+UINT32
 EFIAPI
 DumpGasStruct (
   IN UINT8*        Ptr,
-  IN UINT32        Indent
+  IN UINT32        Indent,
+  IN UINT32        Length
   )
 {
   Print (L"\n");
-  ParseAcpi (
-    TRUE,
-    Indent,
-    NULL,
-    Ptr,
-    GAS_LENGTH,
-    PARSER_PARAMS (GasParser)
-    );
+  return ParseAcpi (
+           TRUE,
+           Indent,
+           NULL,
+           Ptr,
+           Length,
+           PARSER_PARAMS (GasParser)
+           );
 }
 
 /**
@@ -621,7 +625,7 @@ DumpGas (
   IN UINT8*        Ptr
   )
 {
-  DumpGasStruct (Ptr, 2);
+  DumpGasStruct (Ptr, 2, GAS_LENGTH);
 }
 
 /**
diff --git a/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.h b/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.h
index 7657892d9f..20ca358bdd 100644
--- a/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.h
+++ b/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.h
@@ -405,12 +405,16 @@ ParseAcpi (
 
   @param [in] Ptr     Pointer to the start of the buffer.
   @param [in] Indent  Number of spaces to indent the output.
+  @param [in] Length  Length of the GAS structure buffer.
+
+  @retval Number of bytes parsed.
 **/
-VOID
+UINT32
 EFIAPI
 DumpGasStruct (
   IN UINT8*        Ptr,
-  IN UINT32        Indent
+  IN UINT32        Indent,
+  IN UINT32        Length
   );
 
 /**
diff --git a/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Dbg2/Dbg2Parser.c b/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Dbg2/Dbg2Parser.c
index 1efcbd40f8..c6929695a1 100644
--- a/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Dbg2/Dbg2Parser.c
+++ b/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Dbg2/Dbg2Parser.c
@@ -134,7 +134,7 @@ DumpDbgDeviceInfo (
   AddrSize = (UINT32*)(Ptr + (*AddrSizeOffset));
   while (Index < (*GasCount)) {
     PrintFieldName (4, L"BaseAddressRegister");
-    DumpGasStruct (DataPtr, 4);
+    DumpGasStruct (DataPtr, 4, GAS_LENGTH);
     PrintFieldName (4, L"Address Size");
     Print (L"0x%x\n", AddrSize[Index]);
     DataPtr += GAS_LENGTH;