Use ReadUnaligned16 function to access the buffer which is pointed by a possible unaligned pointer.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13879 6f19259b-4bc3-4df7-8a09-765794883524

1 files changed, 11 insertions, 5 deletions

diff --git a/IntelFrameworkModulePkg/Csm/BiosThunk/VideoDxe/BiosVideo.c b/IntelFrameworkModulePkg/Csm/BiosThunk/VideoDxe/BiosVideo.c
index cc53355e75..83c7bf7d1c 100644
--- a/IntelFrameworkModulePkg/Csm/BiosThunk/VideoDxe/BiosVideo.c
+++ b/IntelFrameworkModulePkg/Csm/BiosThunk/VideoDxe/BiosVideo.c
@@ -1262,6 +1262,7 @@ BiosVideoCheckForVbe (
   EFI_STATUS                             Status;

   EFI_IA32_REGISTER_SET                  Regs;

   UINT16                                 *ModeNumberPtr;

+  UINT16                                 VbeModeNumber;

   BOOLEAN                                ModeFound;

   BOOLEAN                                EdidFound;

   BIOS_VIDEO_MODE_DATA                   *ModeBuffer;

@@ -1477,12 +1478,17 @@ BiosVideoCheckForVbe (
 

   PreferMode = 0;

   ModeNumber = 0;

-

-  for (; *ModeNumberPtr != VESA_BIOS_EXTENSIONS_END_OF_MODE_LIST; ModeNumberPtr++) {

+  

+  //

+  // ModeNumberPtr may be not 16-byte aligned, so ReadUnaligned16 is used to access the buffer pointed by ModeNumberPtr.

+  //

+  for (VbeModeNumber = ReadUnaligned16 (ModeNumberPtr);

+       VbeModeNumber != VESA_BIOS_EXTENSIONS_END_OF_MODE_LIST;

+       VbeModeNumber = ReadUnaligned16 (++ModeNumberPtr)) {

     //

     // Make sure this is a mode number defined by the VESA VBE specification.  If it isn'tm then skip this mode number.

     //

-    if ((*ModeNumberPtr & VESA_BIOS_EXTENSIONS_MODE_NUMBER_VESA) == 0) {

+    if ((VbeModeNumber & VESA_BIOS_EXTENSIONS_MODE_NUMBER_VESA) == 0) {

       continue;

     }

     //

@@ -1490,7 +1496,7 @@ BiosVideoCheckForVbe (
     //

     gBS->SetMem (&Regs, sizeof (Regs), 0);

     Regs.X.AX = VESA_BIOS_EXTENSIONS_RETURN_MODE_INFORMATION;

-    Regs.X.CX = *ModeNumberPtr;

+    Regs.X.CX = VbeModeNumber;

     gBS->SetMem (BiosVideoPrivate->VbeModeInformationBlock, sizeof (VESA_BIOS_EXTENSIONS_MODE_INFORMATION_BLOCK), 0);

     Regs.X.ES = EFI_SEGMENT ((UINTN) BiosVideoPrivate->VbeModeInformationBlock);

     Regs.X.DI = EFI_OFFSET ((UINTN) BiosVideoPrivate->VbeModeInformationBlock);

@@ -1619,7 +1625,7 @@ BiosVideoCheckForVbe (
     }

 

     CurrentModeData = &ModeBuffer[ModeNumber - 1];

-    CurrentModeData->VbeModeNumber = *ModeNumberPtr;

+    CurrentModeData->VbeModeNumber = VbeModeNumber;

     if (BiosVideoPrivate->VbeInformationBlock->VESAVersion >= VESA_BIOS_EXTENSIONS_VERSION_3_0) {

       CurrentModeData->BytesPerScanLine = BiosVideoPrivate->VbeModeInformationBlock->LinBytesPerScanLine;

       CurrentModeData->Red.Position = BiosVideoPrivate->VbeModeInformationBlock->LinRedFieldPosition;