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: Liming Gao <liming....@intel.com> Cc: Jian J Wang <jian.j.w...@intel.com> Signed-off-by: Hao A Wu <hao.a...@intel.com> --- 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..81a9c9e849 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[in] 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 ( + IN 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 -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#44936): https://edk2.groups.io/g/devel/message/44936 Mute This Topic: https://groups.io/mt/32740915/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-