UefiCpuPkg: Move MigrateGdt from DiscoverMemory to TempRamDone. (CVE-2019-11098)

[mirror_edk2.git] / UefiCpuPkg / SecCore / SecMain.c

diff --git a/UefiCpuPkg/SecCore/SecMain.c b/UefiCpuPkg/SecCore/SecMain.c
index 155be49a60117b46bdce57307232a252ed692014..2416c4ce56b281ad66626ef95d4bbc6c64d8517e 100644 (file)
--- a/UefiCpuPkg/SecCore/SecMain.c
+++ b/UefiCpuPkg/SecCore/SecMain.c
@@ -35,6 +35,43 @@ EFI_PEI_PPI_DESCRIPTOR            mPeiSecPlatformInformationPpi[] = {
   }\r
 };\r
 \r
+/**\r
+  Migrates the Global Descriptor Table (GDT) to permanent memory.\r
+\r
+  @retval   EFI_SUCCESS           The GDT was migrated successfully.\r
+  @retval   EFI_OUT_OF_RESOURCES  The GDT could not be migrated due to lack of available memory.\r
+\r
+**/\r
+EFI_STATUS\r
+MigrateGdt (\r
+  VOID\r
+  )\r
+{\r
+  EFI_STATUS          Status;\r
+  UINTN               GdtBufferSize;\r
+  IA32_DESCRIPTOR     Gdtr;\r
+  VOID                *GdtBuffer;\r
+\r
+  AsmReadGdtr ((IA32_DESCRIPTOR *) &Gdtr);\r
+  GdtBufferSize = sizeof (IA32_SEGMENT_DESCRIPTOR) -1 + Gdtr.Limit + 1;\r
+\r
+  Status =  PeiServicesAllocatePool (\r
+              GdtBufferSize,\r
+              &GdtBuffer\r
+              );\r
+  ASSERT (GdtBuffer != NULL);\r
+  if (EFI_ERROR (Status)) {\r
+    return EFI_OUT_OF_RESOURCES;\r
+  }\r
+\r
+  GdtBuffer = ALIGN_POINTER (GdtBuffer, sizeof (IA32_SEGMENT_DESCRIPTOR));\r
+  CopyMem (GdtBuffer, (VOID *) Gdtr.Base, Gdtr.Limit + 1);\r
+  Gdtr.Base = (UINTN) GdtBuffer;\r
+  AsmWriteGdtr (&Gdtr);\r
+\r
+  return EFI_SUCCESS;\r
+}\r
+\r
 //\r
 // These are IDT entries pointing to 10:FFFFFFE4h.\r
 //\r
@@ -409,6 +446,14 @@ SecTemporaryRamDone (
   //\r
   State = SaveAndDisableInterrupts ();\r
 \r
+  //\r
+  // Migrate GDT before NEM near down\r
+  //\r
+  if (PcdGetBool (PcdMigrateTemporaryRamFirmwareVolumes)) {\r
+    Status = MigrateGdt ();\r
+    ASSERT_EFI_ERROR (Status);\r
+  }\r
+\r
   //\r
   // Disable Temporary RAM after Stack and Heap have been migrated at this point.\r
   //\r