[storage/fuzz] fix mmr_journaled fuzz test #2746
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| // Truncate tracking variables to match recovered state | ||
| let recovered_leaves = new_mmr.leaves().as_u64() as usize; | ||
| leaves.truncate(recovered_leaves); | ||
| historical_sizes.truncate(recovered_leaves); |
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Wrong tracking data after pop-add-reinit sequence
Low Severity
The truncation logic assumes leaves[0..recovered_leaves] matches the recovered MMR's leaves. This breaks after a Pop-Add sequence without sync. For example: sync with [A,B], pop one leaf giving [A], add C giving [A,C], then Reinit recovers 2 leaves. leaves.truncate(2) keeps [A,C] but the recovered MMR has [A,B]. Subsequent Proof operations use wrong element data (C instead of B), causing spurious verification failures that misleadingly suggest bugs in the MMR implementation.
🔬 Verification Test
Why verification test was not possible: This is a fuzz test infrastructure issue in a Rust project that requires the full commonware-storage crate and its dependencies to compile and run. The bug manifests as spurious assertion failures during fuzz testing when a specific operation sequence (sync → pop → add → reinit) occurs, which cannot be easily unit tested in isolation without the full fuzzing framework.
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pop does a sync, so this should be fine.
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The crash is not reproduced anymore |
Codecov Report✅ All modified and coverable lines are covered by tests. @@ Coverage Diff @@
## main #2746 +/- ##
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Coverage 93.20% 93.20%
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Files 372 372
Lines 113359 113359
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Hits 105655 105655
Misses 7704 7704 Continue to review full report in Codecov by Sentry.
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