Add initial wallet_bdb_parser corpus

[Sjors]

Generated on Ubuntu 23.04 using Clang 15.0.7 and libFuzzer --with-sanitizers=fuzzer

Generated by running the wallet_bdb_parser target in https://github.com/bitcoin/bitcoin/pull/26606 for about a day on AMD Ryzen 9 7950X.

I used test/fuzz/test_runner.py --m_dir which reduced the inputs from 1210 (200KB) to 116 (2 KB).

I wonder if it makes sense to manually generate some inputs based on real (testnet) wallets.

[Sjors]

cc @achow101 @thecharlatan

[maflcko]

I wonder if it makes sense to manually generate some inputs based on real (testnet) wallets.

This should be trivially possible by removing the use of ConsumeRandomLengthByteVector/FuzzedDataProvider and replace it with outfile << Span{buffer};

[Sjors]

Pushed a commit that contains a wallet and a crash. Let me know if it's non-trivial to reproduce.

[Sjors]

bda20e7f3777a147f944da4a50b9147e68b7f4b0 produces a UndefinedBehaviorSanitizer for me with https://github.com/bitcoin/bitcoin/pull/26606/commits/a7508fedcb529324bb1009455151800138e09022.

[maflcko]

Are you still working on this?

[Sjors]

Probably not, will the commits up for grabs if someone wants to take a stab.