Summary

runtime/src/drivers.rs → initialize_dpe() hardcodes svn: 0 when replaying ROM measurement log entries into DPE, even though MeasurementLogEntry stores the SVN provided by the caller. This means measurements stashed during ROM phase lose their SVN in DPE — affecting CDI derivation, X.509 certificates, and anti-rollback guarantees.

Branch

main branch of caliptra-sw (commit 083d7946), which uses caliptra-dpe at commit cfc9a71 (on caliptra-dpe main).

Note: The main-2.x branch pins an older DPE (f56f66e, runtime-1.2 branch) that does not have SVN in DeriveContextCmd, so this bug only manifests on the main branch which uses the newer DPE with SVN support.

Affected Code

The Bug — runtime/src/drivers.rs lines 713-726

ROM measurement log replay in initialize_dpe() hardcodes svn: 0:

```rust
let result = DeriveContextCmd {
// ...
tci_type,
target_locality: pl0_pauser_locality,
svn: 0, // <--- BUG: should be measurement_log_entry.svn
}
```

ROM correctly stores SVN

rom/dev/src/flow/cold_reset/fw_processor.rs saves stash_measurement.svn into MeasurementLogEntry.svn.

RT stash correctly passes SVN

runtime/src/stash_measurement.rs line 66 passes svn from the caller to DeriveContextCmd.

Impact

1. CDI derivation is wrong — The derived CDI does not reflect the actual SVN of ROM-phase measured components.
2. Certificates misreport SVN — X.509 MultiTcbInfo shows SVN=0 for ROM-phase measurements regardless of actual value.
3. Anti-rollback is weakened — SVN-based anti-rollback cannot detect firmware rollback for ROM-phase measured components.
4. Inconsistency — The same STASH_MEASUREMENT gets different DPE treatment depending on whether it was sent before or after RT firmware is running.

Reproduction

Send STASH_MEASUREMENT with svn=42 via both ROM and RT paths, then compare the DPE leaf certs:

ROM-stash path TcbInfo entries:
  tci_type: TEST, svn: 0      <-- BUG: should be 42

RT-stash path TcbInfo entries:
  tci_type: TEST, svn: 42     <-- correct

Proposed Fix

One-line change in initialize_dpe():

```rust
svn: measurement_log_entry.svn, // was: svn: 0,
```