Acked-by: Michael Kubacki <michael.kuba...@microsoft.com>
Inline code comment below.
On 4/12/2023 5:25 PM, Abhimanyu Singh wrote:
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4410
Inside TcgMorLockSmm.c, the SetVariableCheckHandlerMorLock() function
contains a scenario to prevent a possible dictionary attack on the MorLock
Key in accordance with the TCG Platform Reset Mitigation Spec v1.10.
The mechanism to prevent this attack must also change the MorLock Variable
Value to 0x01 to indicate Locked Without Key.
Cc: Jian J Wang <jian.j.w...@intel.com>
Cc: Liming Gao <gaolim...@byosoft.com.cn>
Signed-off-by: Abhi Singh <abhi.si...@arm.com>
---
MdeModulePkg/Universal/Variable/RuntimeDxe/TcgMorLockSmm.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/TcgMorLockSmm.c
b/MdeModulePkg/Universal/Variable/RuntimeDxe/TcgMorLockSmm.c
index da1105ff073e..a76db18ef877 100644
--- a/MdeModulePkg/Universal/Variable/RuntimeDxe/TcgMorLockSmm.c
+++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/TcgMorLockSmm.c
@@ -312,6 +312,10 @@ SetVariableCheckHandlerMorLock (
mMorLockState = MorLockStateLocked;
mMorLockKeyEmpty = TRUE;
ZeroMem (mMorLockKey, sizeof (mMorLockKey));
+ //
+ // Update value to reflect locked without key
+ //
+ SetMorLockVariable (MOR_LOCK_DATA_LOCKED_WITHOUT_KEY);
I know the TCG Reset Attack Mitigation Specification requires
EFI_ACCESS_DENIED to be returned from this function in this case but
SetMorLockVariable() returns a status code.
I suggest capturing that followed by an ASSERT_EFI_ERROR (Status) to at
least help raise visibility of unexpected errors in builds with asserts
enabled.
return EFI_ACCESS_DENIED;
}
}
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