Fatal error: Unknown frame type in `DiffOracle.parseFrameType` during differential execution (DumplingDiffOracle)

Summary

Fuzzilli crashes with a fatal error when the Dumpling differential oracle encounters an unknown frame type.

The crash happens in parseFrameType because a new/unknown frame prefix appeared in the dump that is not handled in the switch.

Crash Details

Fuzzilli/Oracle.swift:184: Fatal error: Unknown frame type
💣 Program crashed: Illegal instruction at 0x00007ad78b2e2af8

Platform: x86_64 Linux (Ubuntu 22.04.5 LTS)

Thread 5 crashed:
 0  _assertionFailure(_:_:file:line:flags:) + 264 in libswiftCore.so
 1  parseFrameType #1 (_:) in static DiffOracle.parseDiffFrame(_:_:_:_:) + 292
    at Sources/Fuzzilli/DumplingDiffOracle/Oracle.swift:184:17

   182│ case "---D": .deoptTurbofan
   183│ default:
   184│     fatalError("Unknown frame type")
      │     ▲
   185│ }

... (full backtrace continues through parseFullFrames → relate → DiffExecution.diff → executeDifferentialIfNeeded)

Backtrace key points:

• DiffOracle.parseDiffFrame
• DiffOracle.parseFullFrames
• DiffOracle.relate(optIn:with:)
• DiffExecution.diff(...)
• Fuzzer.executeDifferentialIfNeeded → Fuzzer.execute → Fuzzer.importProgram

Actual Behavior

Hard fatalError → immediate crash of the fuzzer process.

Commit ID

cbade79edaf1dae0c233890b7957f560008d2c63

Environment

• Proxmox PVE Ubuntu 22.04 VM
• 60 cores
• 64 GB Ram
• 150gb nvme

Command Used:

swift run -c release FuzzilliCli --profile=v8Dumpling --jobs=60 --storagePath=/home/saqib/Desktop/dump --swarmTesting --forDifferentialFuzzing /home/{$USER}/Desktop/v8/out/fuzzbuild/d8

Start in Sources/Fuzzilli/DumplingDiffOracle/Oracle.swift at parseDiffFrame and parseFrameType, then trace parseFullFrames and relate. Reproduce with the v8Dumpling differential-fuzzing command and inspect the unknown dump prefix; done means the encountered frame no longer causes an immediate fuzzer crash and its handling is validated.