Testnet - SegWit bech32 address transaction - Assertion `tx.wit.vtxinwit.size() <= tx.vin.size()' failed

[phoreproject]

Testnet - SegWit bech32 address transaction - Assertion `tx.wit.vtxinwit.size() <= tx.vin.size()' failed

[tohsnoom]

I just had this happen again while sending to a bech32 address, the client crashed the same assert failure:

Assertion failed: (tx.wit.vtxinwit.size() <= tx.vin.size()), function SerializeTransaction, file ./primitives/transaction.h, line 348.

The transaction was similar to the above, and was sending to a bech32 address within it's own wallet.

[tohsnoom]

I tried sending slightly smaller amounts of 250,000 tPHR to an internal wallet bech32 address, and did the same transaction twice. The first one succeeded, the 2nd one crashed with the same assertion.

[wqking]

I used the GUI to send 100K tPHR several times and didn't reproduce this problem. But I doubt that it's related CLI/GUI. Seems this happens randomly so we'd better see how to reproduce it reliably.

@meyer9
For most resizing of vtxinwit, they are vtxinwit.resize(tx.vin.size()), so they should be no problem.
The only possible problem is that, in main.cpp, function UpdateUncommittedBlockStructures, there is a line block.vtx[1].wit.vtxinwit[0].scriptWitness.stack.resize(1), note in previous code it's block.vtx[0], not 1.
That function is called by GenerateCoinbaseCommitment, and GenerateCoinbaseCommitment is called only once, in miner.cpp, function CreateNewBlock.

        pblock->vtx[0].vin[0].scriptSig = CScript() << nHeight << OP_0;
        pblocktemplate->vchCoinbaseCommitment = GenerateCoinbaseCommitment(*pblock, pindexPrev);

The latest code has changed the vtx index from 0 to 1 in GenerateCoinbaseCommitment, but the previous line only operates on index 0, not 1.
I'm not sure if it's the problem.

[tohsnoom]

I've been able to do this mulitple times pretty reliably. I'd suggest you do the following:

1. Take a large amount of tPHR and split it into 2000+ small inputs with the UTXO split option.
2. Send a transaction to a bech32 address that requires a very large number of those inputs to send the required amount. If you still have a large input, use that first, then send more similar transactions right after the first one, thus forcing it to use all the smaller inputs.

[tohsnoom]

As another data point, I just replicated it again. First I sent a series of 500,000 tPHR transactions to bech32 addresses, all succeeded.

Then I tried a 2 million tPHR transaction and that gave a "transaction too large" error message (that's as designed).

Then I backed off the amount to 1 million, and the wallet crashed. Here are the inputs it attempted to use when it crashed:

2018-10-25 17:58:36 CWallet::SelectCoinsMinConf best subset: 250000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 4.1901165 - total 1000004.1901165
2018-10-25 17:58:36 keypool reserve 989
2018-10-25 17:58:36 CWallet::SelectCoinsMinConf best subset: 250000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 4.1901165 - total 1000004.1901165
2018-10-25 17:58:36 CWallet::SelectCoinsMinConf best subset: 1000000.00 4.1901165 - total 1000004.1901165

[wqking]

Fixed in PR #130