Hi, more comments on the MigrateGdt() function:
On 07/03/20 13:36, Laszlo Ersek wrote: > Hi, > > this patch contains a bunch of changes that are not related to the main > purpose of the patch. See below. > > On 07/02/20 07:15, Guomin Jiang wrote: >> From: Michael Kubacki <michael.a.kuba...@intel.com> >> >> REF:https://bugzilla.tianocore.org/show_bug.cgi?id=1614 >> >> Moves the GDT and IDT to permanent memory in a memory discovered >> callback. This is done to ensure the GDT and IDT authenticated in >> pre-memory is not fetched from outside a verified location after >> the permanent memory transition. >> >> Cc: Eric Dong <eric.d...@intel.com> >> Cc: Ray Ni <ray...@intel.com> >> Cc: Laszlo Ersek <ler...@redhat.com> >> Cc: Rahul Kumar <rahul1.ku...@intel.com> >> Signed-off-by: Michael Kubacki <michael.a.kuba...@intel.com> >> --- >> UefiCpuPkg/CpuMpPei/CpuMpPei.c | 40 ++++++++++++++++++- >> UefiCpuPkg/CpuMpPei/CpuMpPei.h | 13 ++++++ >> UefiCpuPkg/CpuMpPei/CpuPaging.c | 14 +++++-- >> .../Ia32/ArchExceptionHandler.c | 4 +- >> .../SecPeiCpuException.c | 2 +- >> 5 files changed, 65 insertions(+), 8 deletions(-) >> >> diff --git a/UefiCpuPkg/CpuMpPei/CpuMpPei.c b/UefiCpuPkg/CpuMpPei/CpuMpPei.c >> index 07ccbe7c6a91..2d6f1bc98851 100644 >> --- a/UefiCpuPkg/CpuMpPei/CpuMpPei.c >> +++ b/UefiCpuPkg/CpuMpPei/CpuMpPei.c >> @@ -429,6 +429,44 @@ GetGdtr ( >> AsmReadGdtr ((IA32_DESCRIPTOR *)Buffer); >> } >> >> +/** >> + Migrates the Global Descriptor Table (GDT) to permanent memory. >> + >> + @retval EFI_SUCCESS The GDT was migrated successfully. >> + @retval EFI_OUT_OF_RESOURCES The GDT could not be migrated due to lack >> of available memory. >> + >> +**/ >> +EFI_STATUS >> +EFIAPI >> +MigrateGdt ( >> + VOID >> + ) >> +{ >> + EFI_STATUS Status; >> + UINTN GdtBufferSize; >> + IA32_DESCRIPTOR Gdtr; >> + UINT8 *GdtBuffer; >> + >> + AsmReadGdtr ((IA32_DESCRIPTOR *) &Gdtr); >> + GdtBufferSize = sizeof (IA32_TSS_DESCRIPTOR) + Gdtr.Limit + 1; (6) I don't understand why IA32_TSS_DESCRIPTOR is used in this function. While technically it should not cause problems, "TSS" seems completely irrelevant here. Please use IA32_SEGMENT_DESCRIPTOR instead. (7) The buffer size is too large. "Gdtr.Limit" is an inclusive limit indeed, so the "+1" at the end is justified, for determining the size. However, for the alignment, we only need *at most* sizeof (IA32_SEGMENT_DESCRIPTOR) - 1 bytes. (If the allocation is immediately well-aligned, then we need 0 bytes for ensuring the proper alignment, and not "sizeof (IA32_SEGMENT_DESCRIPTOR)" bytes.) So I suggest GdtBufferSize = sizeof (IA32_SEGMENT_DESCRIPTOR) - 1 + Gdtr.Limit + 1; >> + >> + Status = PeiServicesAllocatePool ( >> + GdtBufferSize, >> + (VOID **) &GdtBuffer >> + ); (8) We have way too much casting back and forth here. Just make "GdtBuffer" a (VOID*), and then you can drop this cast. >> + ASSERT (GdtBuffer != NULL); >> + if (EFI_ERROR (Status)) { >> + return EFI_OUT_OF_RESOURCES; >> + } >> + >> + GdtBuffer = ALIGN_POINTER (GdtBuffer, sizeof (IA32_TSS_DESCRIPTOR)); (9) Same as (6). >> + CopyMem ((VOID *) (UINTN) GdtBuffer, (VOID *) Gdtr.Base, Gdtr.Limit + 1); (10) Same as (8); drop the (VOID *)(UINTN) casts, please. >> + Gdtr.Base = (UINT32)(UINTN) GdtBuffer; (11) The (UINT32) cast is wrong, please drop it. "Gdtr.Base" has type UINTN. Thanks Laszlo >> + AsmWriteGdtr (&Gdtr); >> + >> + return EFI_SUCCESS; >> +} >> + > > So this hunk relates to the main purpose of the patch; OK. > >> /** >> Initializes CPU exceptions handlers for the sake of stack switch >> requirement. >> >> @@ -644,7 +682,7 @@ InitializeCpuMpWorker ( >> &gEfiVectorHandoffInfoPpiGuid, >> 0, >> NULL, >> - (VOID **)&VectorHandoffInfoPpi >> + (VOID **) &VectorHandoffInfoPpi >> ); >> if (Status == EFI_SUCCESS) { >> VectorInfo = VectorHandoffInfoPpi->Info; > > This change is both useless and totally unrelated to the patch. > > (1) Please drop this hunk. > >> diff --git a/UefiCpuPkg/CpuMpPei/CpuMpPei.h b/UefiCpuPkg/CpuMpPei/CpuMpPei.h >> index 7d5c527d6006..5dc956409594 100644 >> --- a/UefiCpuPkg/CpuMpPei/CpuMpPei.h >> +++ b/UefiCpuPkg/CpuMpPei/CpuMpPei.h >> @@ -397,6 +397,19 @@ SecPlatformInformation2 ( >> OUT EFI_SEC_PLATFORM_INFORMATION_RECORD2 *PlatformInformationRecord2 >> ); >> >> +/** >> + Migrates the Global Descriptor Table (GDT) to permanent memory. >> + >> + @retval EFI_SUCCESS The GDT was migrated successfully. >> + @retval EFI_OUT_OF_RESOURCES The GDT could not be migrated due to lack >> of available memory. >> + >> +**/ >> +EFI_STATUS >> +EFIAPI >> +MigrateGdt ( >> + VOID >> + ); >> + >> /** >> Initializes MP and exceptions handlers. >> > > (2) There's no need to declare this function as EFIAPI. Using EFIAPI is > confusing, because it suggests that the interface is called between > modules. But that's not the case, as far as I can tell. Please drop EFIAPI. > >> diff --git a/UefiCpuPkg/CpuMpPei/CpuPaging.c >> b/UefiCpuPkg/CpuMpPei/CpuPaging.c >> index a462e7ee1e38..d0cbebf70bbf 100644 >> --- a/UefiCpuPkg/CpuMpPei/CpuPaging.c >> +++ b/UefiCpuPkg/CpuMpPei/CpuPaging.c >> @@ -152,7 +152,7 @@ GetPhysicalAddressWidth ( >> Get the type of top level page table. >> >> @retval Page512G PML4 paging. >> - @retval Page1G PAE paing. >> + @retval Page1G PAE paging. >> >> **/ >> PAGE_ATTRIBUTE >> @@ -582,7 +582,7 @@ SetupStackGuardPage ( >> } >> >> /** >> - Enabl/setup stack guard for each processor if PcdCpuStackGuard is set to >> TRUE. >> + Enable/setup stack guard for each processor if PcdCpuStackGuard is set to >> TRUE. >> >> Doing this in the memory-discovered callback is to make sure the Stack >> Guard >> feature to cover as most PEI code as possible. > > (3) These changes are valid (they are typo fixes), but they definitely > belong to a separate patch. Please split them off. > > >> @@ -602,8 +602,14 @@ MemoryDiscoveredPpiNotifyCallback ( >> IN VOID *Ppi >> ) >> { >> - EFI_STATUS Status; >> - BOOLEAN InitStackGuard; >> + EFI_STATUS Status; >> + BOOLEAN InitStackGuard; >> + BOOLEAN InterruptState; >> + >> + InterruptState = SaveAndDisableInterrupts (); >> + Status = MigrateGdt (); >> + ASSERT_EFI_ERROR (Status); >> + SetInterruptState (InterruptState); >> >> // >> // Paging must be setup first. Otherwise the exception TSS setup during MP > > This does belong here, OK. > >> diff --git >> a/UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.c >> b/UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.c >> index 1aafb7dac139..903449e0daa9 100644 >> --- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.c >> +++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.c >> @@ -18,8 +18,8 @@ >> **/ >> VOID >> ArchUpdateIdtEntry ( >> - IN IA32_IDT_GATE_DESCRIPTOR *IdtEntry, >> - IN UINTN InterruptHandler >> + OUT IA32_IDT_GATE_DESCRIPTOR *IdtEntry, >> + IN UINTN InterruptHandler >> ) >> { >> IdtEntry->Bits.OffsetLow = (UINT16)(UINTN)InterruptHandler; > > (4) Please split this off to a separate patch. > > (It's OK to create just one other patch named "UefiCpuPkg/CpuMpPei: > trivial cleanups", and to move the IN/OUT update and the typo fixes to > that patch. I'm not requesting that every trivial update be placed in > its own patch, just that the trivial updates be kept separate from a > patch that is supposed to fix a CVE.) > >> diff --git a/UefiCpuPkg/Library/CpuExceptionHandlerLib/SecPeiCpuException.c >> b/UefiCpuPkg/Library/CpuExceptionHandlerLib/SecPeiCpuException.c >> index 20148db74cf8..d4ae153c5742 100644 >> --- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/SecPeiCpuException.c >> +++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/SecPeiCpuException.c >> @@ -87,7 +87,7 @@ InitializeCpuExceptionHandlers ( >> IdtEntryCount = (IdtDescriptor.Limit + 1) / sizeof >> (IA32_IDT_GATE_DESCRIPTOR); >> if (IdtEntryCount > CPU_EXCEPTION_NUM) { >> // >> - // CPU exeption library only setup CPU_EXCEPTION_NUM exception handler >> at most >> + // CPU exception library only setup CPU_EXCEPTION_NUM exception handler >> at most >> // >> IdtEntryCount = CPU_EXCEPTION_NUM; >> } >> > > (5) Same as (3). > > Thanks > Laszlo > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. 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