From 1d12f0e671550b7a1ac8f2ce282779069b94073c Mon Sep 17 00:00:00 2001 From: Krzysztof Koch Date: Thu, 1 Aug 2019 16:44:03 -0700 Subject: [PATCH] ShellPkg: acpiview: GTDT: Prevent buffer overruns Modify the GTDT table parsing logic to prevent reading past the ACPI buffer lengths provided and to make it consistent with other table parsers. This includes converting the do-while loop in ParseAcpiGtdt() into a while loop. Remove a check which ensures that the entire Platform GT Block Structure buffer has been parsed. The ACPI specification does not ban from defining buffers which are larger than the size indicated by the count and sizes of substructures which constitute it. Change the data type of the Length parameter to the DumpGTBlock() function to reflect the width of the respective ACPI structure's field. References: - ACPI 6.3, January 2019, Table 5-124 Signed-off-by: Krzysztof Koch Reviewed-by: Alexei Fedorov Reviewed-by: Zhichao Gao Reviewed-by: Sami Mujawar --- .../Parsers/Gtdt/GtdtParser.c | 151 +++++++++--------- 1 file changed, 78 insertions(+), 73 deletions(-) diff --git a/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Gtdt/GtdtParser.c b/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Gtdt/GtdtParser.c index 1e5b5764f5..57174e14c8 100644 --- a/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Gtdt/GtdtParser.c +++ b/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Gtdt/GtdtParser.c @@ -23,7 +23,6 @@ STATIC CONST UINT8* PlatformTimerType; STATIC CONST UINT16* PlatformTimerLength; STATIC CONST UINT32* GtBlockTimerCount; STATIC CONST UINT32* GtBlockTimerOffset; -STATIC CONST UINT16* GtBlockLength; STATIC ACPI_DESCRIPTION_HEADER_INFO AcpiHdrInfo; /** @@ -127,7 +126,7 @@ STATIC CONST ACPI_PARSER GtPlatformTimerHeaderParser[] = { **/ STATIC CONST ACPI_PARSER GtBlockParser[] = { {L"Type", 1, 0, L"%d", NULL, NULL, NULL, NULL}, - {L"Length", 2, 1, L"%d", NULL, (VOID**)&GtBlockLength, NULL, NULL}, + {L"Length", 2, 1, L"%d", NULL, NULL, NULL, NULL}, {L"Reserved", 1, 3, L"%x", NULL, NULL, NULL, NULL}, {L"Physical address (CntCtlBase)", 8, 4, L"0x%lx", NULL, NULL, NULL, NULL}, {L"Timer Count", 4, 12, L"%d", NULL, (VOID**)&GtBlockTimerCount, @@ -168,56 +167,43 @@ STATIC CONST ACPI_PARSER SBSAGenericWatchdogParser[] = { /** This function parses the Platform GT Block. - @param [in] Ptr Pointer to the start of the GT Block data. - @param [in] Length Length of the GT Block structure. + @param [in] Ptr Pointer to the start of the GT Block data. + @param [in] Length Length of the GT Block structure. **/ STATIC VOID DumpGTBlock ( IN UINT8* Ptr, - IN UINT32 Length + IN UINT16 Length ) { UINT32 Index; UINT32 Offset; - UINT32 GTBlockTimerLength; - - Offset = ParseAcpi ( - TRUE, - 2, - "GT Block", - Ptr, - Length, - PARSER_PARAMS (GtBlockParser) - ); - GTBlockTimerLength = (*GtBlockLength - Offset) / (*GtBlockTimerCount); - Length -= Offset; - - if (*GtBlockTimerCount != 0) { - Ptr += (*GtBlockTimerOffset); - Index = 0; - while ((Index < (*GtBlockTimerCount)) && (Length >= GTBlockTimerLength)) { - Offset = ParseAcpi ( - TRUE, - 2, - "GT Block Timer", - Ptr, - GTBlockTimerLength, - PARSER_PARAMS (GtBlockTimerParser) - ); - // Increment by GT Block Timer structure size - Ptr += Offset; - Length -= Offset; - Index++; - } - if (Length != 0) { - IncrementErrorCount (); - Print ( - L"ERROR:GT Block Timer length mismatch. Unparsed %d bytes.\n", - Length - ); - } + ParseAcpi ( + TRUE, + 2, + "GT Block", + Ptr, + Length, + PARSER_PARAMS (GtBlockParser) + ); + + Offset = *GtBlockTimerOffset; + Index = 0; + + // Parse the specified number of GT Block Timer Structures or the GT Block + // Structure buffer length. Whichever is minimum. + while ((Index++ < *GtBlockTimerCount) && + (Offset < Length)) { + Offset += ParseAcpi ( + TRUE, + 2, + "GT Block Timer", + Ptr + Offset, + Length - Offset, + PARSER_PARAMS (GtBlockTimerParser) + ); } } @@ -270,6 +256,7 @@ ParseAcpiGtdt ( ) { UINT32 Index; + UINT32 Offset; UINT8* TimerPtr; if (!Trace) { @@ -285,36 +272,54 @@ ParseAcpiGtdt ( PARSER_PARAMS (GtdtParser) ); - if (*GtdtPlatformTimerCount != 0) { - TimerPtr = Ptr + (*GtdtPlatformTimerOffset); - Index = 0; - do { - // Parse the Platform Timer Header - ParseAcpi ( - FALSE, - 0, - NULL, - TimerPtr, - 4, // GT Platform Timer structure header length. - PARSER_PARAMS (GtPlatformTimerHeaderParser) + TimerPtr = Ptr + *GtdtPlatformTimerOffset; + Offset = *GtdtPlatformTimerOffset; + Index = 0; + + // Parse the specified number of Platform Timer Structures or the GTDT + // buffer length. Whichever is minimum. + while ((Index++ < *GtdtPlatformTimerCount) && + (Offset < AcpiTableLength)) { + // Parse the Platform Timer Header to obtain Length and Type + ParseAcpi ( + FALSE, + 0, + NULL, + TimerPtr, + AcpiTableLength - Offset, + PARSER_PARAMS (GtPlatformTimerHeaderParser) + ); + + // Make sure the Platform Timer is inside the table. + if ((Offset + *PlatformTimerLength) > AcpiTableLength) { + IncrementErrorCount (); + Print ( + L"ERROR: Invalid Platform Timer Structure length. " \ + L"PlatformTimerLength = %d. RemainingTableBufferLength = %d. " \ + L"GTDT parsing aborted.\n", + *PlatformTimerLength, + AcpiTableLength - Offset ); - switch (*PlatformTimerType) { - case EFI_ACPI_6_2_GTDT_GT_BLOCK: - DumpGTBlock (TimerPtr, *PlatformTimerLength); - break; - case EFI_ACPI_6_2_GTDT_SBSA_GENERIC_WATCHDOG: - DumpWatchdogTimer (TimerPtr, *PlatformTimerLength); - break; - default: - IncrementErrorCount (); - Print ( - L"ERROR: INVALID Platform Timer Type = %d\n", - *PlatformTimerType - ); - break; - } // switch - TimerPtr += (*PlatformTimerLength); - Index++; - } while (Index < *GtdtPlatformTimerCount); - } + return; + } + + switch (*PlatformTimerType) { + case EFI_ACPI_6_3_GTDT_GT_BLOCK: + DumpGTBlock (TimerPtr, *PlatformTimerLength); + break; + case EFI_ACPI_6_3_GTDT_SBSA_GENERIC_WATCHDOG: + DumpWatchdogTimer (TimerPtr, *PlatformTimerLength); + break; + default: + IncrementErrorCount (); + Print ( + L"ERROR: Invalid Platform Timer Type = %d\n", + *PlatformTimerType + ); + break; + } // switch + + TimerPtr += *PlatformTimerLength; + Offset += *PlatformTimerLength; + } // while } -- 2.39.2