[edk2-devel] [RESEND PATCH 1/1] MdeModulePkg: Fix PiSmmCore integer over- and underflows.
Gerd Hoffmann
kraxel at redhat.com
Tue Oct 4 14:27:08 UTC 2022
Prevents potential math over and underflows when comparing buffers
for SMM validity.
Original patch uploaded to bugzilla by Bret Barkelew <bret at corthon.com>.
I've adapted the patch to latest master, uncristified, dropped MU
comments.
Ref: CVE-2021-38578
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3387
Signed-off-by: Gerd Hoffmann <kraxel at redhat.com>
---
MdeModulePkg/Core/PiSmmCore/PiSmmCore.inf | 1 +
MdeModulePkg/Core/PiSmmCore/PiSmmIpl.inf | 1 +
MdeModulePkg/Core/PiSmmCore/PiSmmCore.h | 1 +
MdeModulePkg/Core/PiSmmCore/PiSmmCore.c | 32 ++++++++++++++++-------
MdeModulePkg/Core/PiSmmCore/PiSmmIpl.c | 10 +++++--
5 files changed, 34 insertions(+), 11 deletions(-)
diff --git a/MdeModulePkg/Core/PiSmmCore/PiSmmCore.inf b/MdeModulePkg/Core/PiSmmCore/PiSmmCore.inf
index c8bfae3860fc..3df44b38f13c 100644
--- a/MdeModulePkg/Core/PiSmmCore/PiSmmCore.inf
+++ b/MdeModulePkg/Core/PiSmmCore/PiSmmCore.inf
@@ -60,6 +60,7 @@ [LibraryClasses]
PerformanceLib
HobLib
SmmMemLib
+ SafeIntLib
[Protocols]
gEfiDxeSmmReadyToLockProtocolGuid ## UNDEFINED # SmiHandlerRegister
diff --git a/MdeModulePkg/Core/PiSmmCore/PiSmmIpl.inf b/MdeModulePkg/Core/PiSmmCore/PiSmmIpl.inf
index 6109d6b5449c..ddeb39cee266 100644
--- a/MdeModulePkg/Core/PiSmmCore/PiSmmIpl.inf
+++ b/MdeModulePkg/Core/PiSmmCore/PiSmmIpl.inf
@@ -46,6 +46,7 @@ [LibraryClasses]
DxeServicesLib
PcdLib
ReportStatusCodeLib
+ SafeIntLib
[Protocols]
gEfiSmmBase2ProtocolGuid ## PRODUCES
diff --git a/MdeModulePkg/Core/PiSmmCore/PiSmmCore.h b/MdeModulePkg/Core/PiSmmCore/PiSmmCore.h
index 71422b9dfcdf..b8a490a8c3b5 100644
--- a/MdeModulePkg/Core/PiSmmCore/PiSmmCore.h
+++ b/MdeModulePkg/Core/PiSmmCore/PiSmmCore.h
@@ -54,6 +54,7 @@
#include <Library/PerformanceLib.h>
#include <Library/HobLib.h>
#include <Library/SmmMemLib.h>
+#include <Library/SafeIntLib.h>
#include "PiSmmCorePrivateData.h"
#include "HeapGuard.h"
diff --git a/MdeModulePkg/Core/PiSmmCore/PiSmmCore.c b/MdeModulePkg/Core/PiSmmCore/PiSmmCore.c
index 9e5c6cbe33dd..5ef8b31ee361 100644
--- a/MdeModulePkg/Core/PiSmmCore/PiSmmCore.c
+++ b/MdeModulePkg/Core/PiSmmCore/PiSmmCore.c
@@ -610,6 +610,7 @@ SmmEndOfS3ResumeHandler (
@param[in] Size2 Size of Buff2
@retval TRUE Buffers overlap in memory.
+ @retval TRUE Math error.
@retval FALSE Buffer doesn't overlap.
**/
@@ -621,11 +622,21 @@ InternalIsBufferOverlapped (
IN UINTN Size2
)
{
+ UINTN End1;
+ UINTN End2;
+
+ // Prevents potential math over and underflows.
+ if (EFI_ERROR (SafeUintnAdd ((UINTN)Buff1, Size1, &End1)) ||
+ EFI_ERROR (SafeUintnAdd ((UINTN)Buff2, Size2, &End2)))
+ {
+ return TRUE;
+ }
+
//
// If buff1's end is less than the start of buff2, then it's ok.
// Also, if buff1's start is beyond buff2's end, then it's ok.
//
- if (((Buff1 + Size1) <= Buff2) || (Buff1 >= (Buff2 + Size2))) {
+ if ((End1 <= (UINTN)Buff2) || ((UINTN)Buff1 >= End2)) {
return FALSE;
}
@@ -699,7 +710,10 @@ SmmEntryPoint (
(UINT8 *)gSmmCorePrivate,
sizeof (*gSmmCorePrivate)
);
- if (!SmmIsBufferOutsideSmmValid ((UINTN)CommunicationBuffer, BufferSize) || IsOverlapped) {
+ if (!SmmIsBufferOutsideSmmValid ((UINTN)CommunicationBuffer, BufferSize) ||
+ IsOverlapped ||
+ EFI_ERROR (SafeUintnSub (BufferSize, OFFSET_OF (EFI_SMM_COMMUNICATE_HEADER, Data), &BufferSize)))
+ {
//
// If CommunicationBuffer is not in valid address scope,
// or there is overlap between gSmmCorePrivate and CommunicationBuffer,
@@ -709,13 +723,13 @@ SmmEntryPoint (
gSmmCorePrivate->ReturnStatus = EFI_ACCESS_DENIED;
} else {
CommunicateHeader = (EFI_SMM_COMMUNICATE_HEADER *)CommunicationBuffer;
- BufferSize -= OFFSET_OF (EFI_SMM_COMMUNICATE_HEADER, Data);
- Status = SmiManage (
- &CommunicateHeader->HeaderGuid,
- NULL,
- CommunicateHeader->Data,
- &BufferSize
- );
+ // BufferSize was updated by the SafeUintnSub() call above.
+ Status = SmiManage (
+ &CommunicateHeader->HeaderGuid,
+ NULL,
+ CommunicateHeader->Data,
+ &BufferSize
+ );
//
// Update CommunicationBuffer, BufferSize and ReturnStatus
// Communicate service finished, reset the pointer to CommBuffer to NULL
diff --git a/MdeModulePkg/Core/PiSmmCore/PiSmmIpl.c b/MdeModulePkg/Core/PiSmmCore/PiSmmIpl.c
index 4f00cebaf5ed..f08ca55e26b7 100644
--- a/MdeModulePkg/Core/PiSmmCore/PiSmmIpl.c
+++ b/MdeModulePkg/Core/PiSmmCore/PiSmmIpl.c
@@ -34,6 +34,7 @@
#include <Library/UefiRuntimeLib.h>
#include <Library/PcdLib.h>
#include <Library/ReportStatusCodeLib.h>
+#include <Library/SafeIntLib.h>
#include "PiSmmCorePrivateData.h"
@@ -1354,6 +1355,7 @@ SmmSplitSmramEntry (
@param[in] ReservedRangeToCompare Pointer to EFI_SMM_RESERVED_SMRAM_REGION to compare.
@retval TRUE There is overlap.
+ @retval TRUE Math error.
@retval FALSE There is no overlap.
**/
@@ -1366,8 +1368,12 @@ SmmIsSmramOverlap (
UINT64 RangeToCompareEnd;
UINT64 ReservedRangeToCompareEnd;
- RangeToCompareEnd = RangeToCompare->CpuStart + RangeToCompare->PhysicalSize;
- ReservedRangeToCompareEnd = ReservedRangeToCompare->SmramReservedStart + ReservedRangeToCompare->SmramReservedSize;
+ // Prevents potential math over and underflows.
+ if (EFI_ERROR (SafeUint64Add ((UINT64)RangeToCompare->CpuStart, RangeToCompare->PhysicalSize, &RangeToCompareEnd)) ||
+ EFI_ERROR (SafeUint64Add ((UINT64)ReservedRangeToCompare->SmramReservedStart, ReservedRangeToCompare->SmramReservedSize, &ReservedRangeToCompareEnd)))
+ {
+ return TRUE;
+ }
if ((RangeToCompare->CpuStart >= ReservedRangeToCompare->SmramReservedStart) &&
(RangeToCompare->CpuStart < ReservedRangeToCompareEnd))
--
2.37.3
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