MdeModulePkg/String.c: Zero memory before free (CVE-2019-14558)

[mirror_edk2.git] / MdeModulePkg / Universal / BdsDxe / Language.c

/** @file\r
  Language settings\r
\r
Copyright (c) 2004 - 2018, Intel Corporation. All rights reserved.<BR>\r
SPDX-License-Identifier: BSD-2-Clause-Patent\r
\r
**/\r
\r
#include "Bds.h"\r
#define ISO_639_2_ENTRY_SIZE 3\r
\r
/**\r
  Check if lang is in supported language codes according to language string.\r
\r
  This code is used to check if lang is in in supported language codes. It can handle\r
  RFC4646 and ISO639 language tags.\r
  In ISO639 language tags, take 3-characters as a delimitation to find matched string.\r
  In RFC4646 language tags, take semicolon as a delimitation to find matched string.\r
\r
  For example:\r
    SupportedLang  = "engfraengfra"\r
    Iso639Language = TRUE\r
    Lang           = "eng", the return value is "TRUE", or\r
    Lang           = "chs", the return value is "FALSE".\r
  Another example:\r
    SupportedLang  = "en;fr;en-US;fr-FR"\r
    Iso639Language = FALSE\r
    Lang           = "en", the return value is "TRUE", or\r
    Lang           = "zh", the return value is "FALSE".\r
\r
  @param  SupportedLang               Platform supported language codes.\r
  @param  Lang                        Configured language.\r
  @param  Iso639Language              A bool value to signify if the handler is operated on ISO639 or RFC4646.\r
\r
  @retval TRUE  lang is in supported language codes.\r
  @retval FALSE lang is not in supported language codes.\r
\r
**/\r
BOOLEAN\r
IsLangInSupportedLangCodes(\r
  IN  CHAR8            *SupportedLang,\r
  IN  CHAR8            *Lang,\r
  IN  BOOLEAN          Iso639Language\r
  )\r
{\r
  UINTN    Index;\r
  UINTN    CompareLength;\r
  UINTN    LanguageLength;\r
\r
  if (Iso639Language) {\r
    CompareLength = ISO_639_2_ENTRY_SIZE;\r
    for (Index = 0; Index < AsciiStrLen (SupportedLang); Index += CompareLength) {\r
      if (AsciiStrnCmp (Lang, SupportedLang + Index, CompareLength) == 0) {\r
        //\r
        // Successfully find the Lang string in SupportedLang string.\r
        //\r
        return TRUE;\r
      }\r
    }\r
    return FALSE;\r
  } else {\r
    //\r
    // Compare RFC4646 language code\r
    //\r
    for (LanguageLength = 0; Lang[LanguageLength] != '\0'; LanguageLength++);\r
\r
    for (; *SupportedLang != '\0'; SupportedLang += CompareLength) {\r
      //\r
      // Skip ';' characters in SupportedLang\r
      //\r
      for (; *SupportedLang != '\0' && *SupportedLang == ';'; SupportedLang++);\r
      //\r
      // Determine the length of the next language code in SupportedLang\r
      //\r
      for (CompareLength = 0; SupportedLang[CompareLength] != '\0' && SupportedLang[CompareLength] != ';'; CompareLength++);\r
\r
      if ((CompareLength == LanguageLength) &&\r
          (AsciiStrnCmp (Lang, SupportedLang, CompareLength) == 0)) {\r
        //\r
        // Successfully find the Lang string in SupportedLang string.\r
        //\r
        return TRUE;\r
      }\r
    }\r
    return FALSE;\r
  }\r
}\r
\r
/**\r
  Initialize Lang or PlatformLang variable, if Lang or PlatformLang variable is not found,\r
  or it has been set to an unsupported value(not one of platform supported language codes),\r
  set the default language code to it.\r
\r
  @param  LangName                    Language name, L"Lang" or L"PlatformLang".\r
  @param  SupportedLang               Platform supported language codes.\r
  @param  DefaultLang                 Default language code.\r
  @param  Iso639Language              A bool value to signify if the handler is operated on ISO639 or RFC4646,\r
                                      TRUE for L"Lang" LangName or FALSE for L"PlatformLang" LangName.\r
\r
**/\r
VOID\r
InitializeLangVariable (\r
  IN CHAR16     *LangName,\r
  IN CHAR8      *SupportedLang,\r
  IN CHAR8      *DefaultLang,\r
  IN BOOLEAN    Iso639Language\r
  )\r
{\r
  CHAR8       *Lang;\r
\r
  //\r
  // Find current Lang or PlatformLang from EFI Variable.\r
  //\r
  GetEfiGlobalVariable2 (LangName, (VOID **) &Lang, NULL);\r
\r
  //\r
  // If Lang or PlatformLang variable is not found,\r
  // or it has been set to an unsupported value(not one of the supported language codes),\r
  // set the default language code to it.\r
  //\r
  if ((Lang == NULL) || !IsLangInSupportedLangCodes (SupportedLang, Lang, Iso639Language)) {\r
    //\r
    // The default language code should be one of the supported language codes.\r
    //\r
    ASSERT (IsLangInSupportedLangCodes (SupportedLang, DefaultLang, Iso639Language));\r
    BdsDxeSetVariableAndReportStatusCodeOnError (\r
      LangName,\r
      &gEfiGlobalVariableGuid,\r
      EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,\r
      AsciiStrSize (DefaultLang),\r
      DefaultLang\r
      );\r
  }\r
\r
  if (Lang != NULL) {\r
    FreePool (Lang);\r
  }\r
}\r
\r
/**\r
  Determine the current language that will be used\r
  based on language related EFI Variables.\r
\r
  @param LangCodesSettingRequired - If required to set LangCodes variable\r
\r
**/\r
VOID\r
InitializeLanguage (\r
  BOOLEAN LangCodesSettingRequired\r
  )\r
{\r
  EFI_STATUS  Status;\r
  CHAR8       *LangCodes;\r
  CHAR8       *PlatformLangCodes;\r
\r
  LangCodes = (CHAR8 *)PcdGetPtr (PcdUefiVariableDefaultLangCodes);\r
  PlatformLangCodes = (CHAR8 *)PcdGetPtr (PcdUefiVariableDefaultPlatformLangCodes);\r
  if (LangCodesSettingRequired) {\r
    if (!FeaturePcdGet (PcdUefiVariableDefaultLangDeprecate)) {\r
      //\r
      // UEFI 2.1 depricated this variable so we support turning it off\r
      //\r
      Status = gRT->SetVariable (\r
                      L"LangCodes",\r
                      &gEfiGlobalVariableGuid,\r
                      EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,\r
                      AsciiStrSize (LangCodes),\r
                      LangCodes\r
                      );\r
      //\r
      // Platform needs to make sure setting volatile variable before calling 3rd party code shouldn't fail.\r
      //\r
      ASSERT_EFI_ERROR(Status);\r
    }\r
\r
    Status = gRT->SetVariable (\r
                    L"PlatformLangCodes",\r
                    &gEfiGlobalVariableGuid,\r
                    EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,\r
                    AsciiStrSize (PlatformLangCodes),\r
                    PlatformLangCodes\r
                    );\r
    //\r
    // Platform needs to make sure setting volatile variable before calling 3rd party code shouldn't fail.\r
    //\r
    ASSERT_EFI_ERROR(Status);\r
  }\r
\r
  if (!FeaturePcdGet (PcdUefiVariableDefaultLangDeprecate)) {\r
    //\r
    // UEFI 2.1 depricated this variable so we support turning it off\r
    //\r
    InitializeLangVariable (L"Lang", LangCodes, (CHAR8 *) PcdGetPtr (PcdUefiVariableDefaultLang), TRUE);\r
  }\r
  InitializeLangVariable (L"PlatformLang", PlatformLangCodes, (CHAR8 *) PcdGetPtr (PcdUefiVariableDefaultPlatformLang), FALSE);\r
}\r