REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2002
This commit will update the logic in function SmmVariableGetStatistics()
so that the pointer fields ('Next' and 'Name') in structure
VARIABLE_INFO_ENTRY will not be copied into the SMM communication buffer.
Doing so will prevent SMM pointers address from being leaked into non-SMM
environment.
Please note that newly introduced internal function CopyVarInfoEntry()
will not use CopyMem() to copy the whole VARIABLE_INFO_ENTRY structure and
then zero out the 'Next' and 'Name' fields. This is for preventing race
conditions where the pointers value might still be read.
Cc: Star Zeng <[email protected]>
Cc: Liming Gao <[email protected]>
Cc: Jian J Wang <[email protected]>
Signed-off-by: Hao A Wu <[email protected]>
---
V2 patch updates the type of parameter 'DstInfoEntry' from 'in' to 'out'
for the newly added function CopyVarInfoEntry().
MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.c | 33
++++++++++++++++++--
1 file changed, 31 insertions(+), 2 deletions(-)
diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.c
b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.c
index ec463d063e..9b59387e58 100644
--- a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.c
+++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.c
@@ -312,6 +312,35 @@ GetFvbCountAndBuffer (
/**
+ Copy only the meaningful fields of the variable statistics information from
+ source buffer to the destination buffer. Other fields are filled with zero.
+
+ @param[out] DstInfoEntry A pointer to the buffer of destination variable
+ information entry.
+ @param[in] SrcInfoEntry A pointer to the buffer of source variable
+ information entry.
+
+**/
+static
+VOID
+CopyVarInfoEntry (
+ OUT VARIABLE_INFO_ENTRY *DstInfoEntry,
+ IN VARIABLE_INFO_ENTRY *SrcInfoEntry
+ )
+{
+ DstInfoEntry->Next = NULL;
+ DstInfoEntry->Name = NULL;
+
+ CopyGuid (&DstInfoEntry->VendorGuid, &SrcInfoEntry->VendorGuid);
+ DstInfoEntry->Attributes = SrcInfoEntry->Attributes;
+ DstInfoEntry->ReadCount = SrcInfoEntry->ReadCount;
+ DstInfoEntry->WriteCount = SrcInfoEntry->WriteCount;
+ DstInfoEntry->DeleteCount = SrcInfoEntry->DeleteCount;
+ DstInfoEntry->CacheCount = SrcInfoEntry->CacheCount;
+ DstInfoEntry->Volatile = SrcInfoEntry->Volatile;
+}
+
+/**
Get the variable statistics information from the information buffer pointed
by gVariableInfo.
Caution: This function may be invoked at SMM runtime.
@@ -373,7 +402,7 @@ SmmVariableGetStatistics (
*InfoSize = StatisticsInfoSize;
return EFI_BUFFER_TOO_SMALL;
}
- CopyMem (InfoEntry, VariableInfo, sizeof (VARIABLE_INFO_ENTRY));
+ CopyVarInfoEntry (InfoEntry, VariableInfo);
CopyMem (InfoName, VariableInfo->Name, NameSize);
*InfoSize = StatisticsInfoSize;
return EFI_SUCCESS;
@@ -413,7 +442,7 @@ SmmVariableGetStatistics (
return EFI_BUFFER_TOO_SMALL;
}
- CopyMem (InfoEntry, VariableInfo, sizeof (VARIABLE_INFO_ENTRY));
+ CopyVarInfoEntry (InfoEntry, VariableInfo);
CopyMem (InfoName, VariableInfo->Name, NameSize);
*InfoSize = StatisticsInfoSize;
--
2.12.0.windows.1
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