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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
This commit is contained in:
li-elvin 2012-10-24 01:10:47 +00:00
parent 151304d96d
commit e6fa789014
1 changed files with 11 additions and 5 deletions
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14
IntelFrameworkModulePkg/Csm/BiosThunk/VideoDxe/BiosVideo.c
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@ -1262,6 +1262,7 @@ BiosVideoCheckForVbe (
EFI_STATUS Status; EFI_STATUS Status;
EFI_IA32_REGISTER_SET Regs; EFI_IA32_REGISTER_SET Regs;
UINT16 *ModeNumberPtr; UINT16 *ModeNumberPtr;
UINT16 VbeModeNumber;
BOOLEAN ModeFound; BOOLEAN ModeFound;
BOOLEAN EdidFound; BOOLEAN EdidFound;
BIOS_VIDEO_MODE_DATA *ModeBuffer; BIOS_VIDEO_MODE_DATA *ModeBuffer;
@ -1478,11 +1479,16 @@ BiosVideoCheckForVbe (
PreferMode = 0; PreferMode = 0;
ModeNumber = 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. // 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; continue;
} }
// //
@ -1490,7 +1496,7 @@ BiosVideoCheckForVbe (
// //
gBS->SetMem (&Regs, sizeof (Regs), 0); gBS->SetMem (&Regs, sizeof (Regs), 0);
Regs.X.AX = VESA_BIOS_EXTENSIONS_RETURN_MODE_INFORMATION; 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); gBS->SetMem (BiosVideoPrivate->VbeModeInformationBlock, sizeof (VESA_BIOS_EXTENSIONS_MODE_INFORMATION_BLOCK), 0);
Regs.X.ES = EFI_SEGMENT ((UINTN) BiosVideoPrivate->VbeModeInformationBlock); Regs.X.ES = EFI_SEGMENT ((UINTN) BiosVideoPrivate->VbeModeInformationBlock);
Regs.X.DI = EFI_OFFSET ((UINTN) BiosVideoPrivate->VbeModeInformationBlock); Regs.X.DI = EFI_OFFSET ((UINTN) BiosVideoPrivate->VbeModeInformationBlock);
@ -1619,7 +1625,7 @@ BiosVideoCheckForVbe (
} }
CurrentModeData = &ModeBuffer[ModeNumber - 1]; CurrentModeData = &ModeBuffer[ModeNumber - 1];
CurrentModeData->VbeModeNumber = *ModeNumberPtr; CurrentModeData->VbeModeNumber = VbeModeNumber;
if (BiosVideoPrivate->VbeInformationBlock->VESAVersion >= VESA_BIOS_EXTENSIONS_VERSION_3_0) { if (BiosVideoPrivate->VbeInformationBlock->VESAVersion >= VESA_BIOS_EXTENSIONS_VERSION_3_0) {
CurrentModeData->BytesPerScanLine = BiosVideoPrivate->VbeModeInformationBlock->LinBytesPerScanLine; CurrentModeData->BytesPerScanLine = BiosVideoPrivate->VbeModeInformationBlock->LinBytesPerScanLine;
CurrentModeData->Red.Position = BiosVideoPrivate->VbeModeInformationBlock->LinRedFieldPosition; CurrentModeData->Red.Position = BiosVideoPrivate->VbeModeInformationBlock->LinRedFieldPosition;