[bug] lnd crashes when not correct psbt data is used as input

[ziggie1984]

Lnd will crash if the provided psbt (funded psbt) is missing the psbt NonWitnessUtxo or WitnessUtxo field. The problem lies here:
https://github.com/btcsuite/btcd/blob/master/txscript/hashcache.go#L239

We should check the psbt for this data to prevent any crashing of lnd.

I created the following psbt code which has missing utxo information and will therefore lead to an lnd crash

rlncli wallet psbt finalize cHNidP8BAF4CAAAAAQlokRq0L38emcB8Um/7+GXDR8gIJzlWRFOf4/c+xoaUAQAAAAD/////Ab/EPgUAAAAAIlEgfCPRPJzr08tF7NAdPvdArXQbVojQ+UkVL2LBAOgkWpgAAAAAAAAA

As already discussed offline we should solve this issue in lnd, meaning that we should check the psbt there before we attempt to calculate any sighashes.

Your environment

• version of lnd: 0.16 rc3

[ziggie1984]

Part of the stack trace when finializing the psbt:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x8 pc=0x104d216d4]
goroutine 482 [running]:
[github.com/btcsuite/btcd/txscript.NewTxSigHashes(0x140008ce380](http://github.com/btcsuite/btcd/txscript.NewTxSigHashes(0x140008ce380), {0x106480fe0, 0x14000140428})
	/Users/ziggie-pro/working_freetime/btcd/txscript/hashcache.go:243 +0x154
[github.com/btcsuite/btcwallet/wallet.(*Wallet).FinalizePsbt(0x1400037e000](http://github.com/btcsuite/btcwallet/wallet.(*Wallet).FinalizePsbt(0x1400037e000), 0x0, 0x0, 0x140000b5720)
	/Users/ziggie-pro/working_freetime/btcwallet/wallet/psbt.go:397 +0x68

[Roasbeef]

Fixed by #7529

[vindard]

Out of curiosity, why would this txn

{
  "txid": "43c79b969d3e8e6cbe198f5b25e8cd03120372eab26578f486bc6258b8677a57",
  "hash": "653cc4921119c7f127bb56f125163d279376fd6fa0995f3dd91c2a51e8a108ea",
  "version": 2,
  "size": 222,
  "vsize": 141,
  "weight": 561,
  "locktime": 200,
  "vin": [
    {
      "txid": "4853a89d083df152f697aa5d63bcd6919ffaa0213b7736d227eed10fd53c6378",
      "vout": 0,
      "scriptSig": {
        "asm": "",
        "hex": ""
      },
      "txinwitness": [
        "304402202874d54141b3804267cec7320f4a27ddc22e1c17100c7106630ef40e1f01cb4402200527d5491d94887c7178b58dab73153ba5e027a225eb413f8ab660575ee4907401",
        "0384e78028f045c515e8730b67fa96d12e3bd2572d0f312c129872655747f19f40"
      ],
      "sequence": 4294967293
    }
  ],
  "vout": [
    {
      "value": 1.00000000,
      "n": 0,
      "scriptPubKey": {
        "asm": "0 6f7ec5399599d8cfecb5bb5218bd85c6f419fec3",
        "desc": "addr(bcrt1qdalv2wv4n8vvlm94hdfp30v9cm6pnlkrqq5flr)#c6nl327t",
        "hex": "00146f7ec5399599d8cfecb5bb5218bd85c6f419fec3",
        "address": "bcrt1qdalv2wv4n8vvlm94hdfp30v9cm6pnlkrqq5flr",
        "type": "witness_v0_keyhash"
      }
    },
    {
      "value": 48.99997180,
      "n": 1,
      "scriptPubKey": {
        "asm": "0 f2774e8e9922f3c728d2e30dfec006d8cd6fee53",
        "desc": "addr(bcrt1q7fm5ar5eyteuw2xjuvxlasqxmrxklmjnx83cat)#vt5cse08",
        "hex": "0014f2774e8e9922f3c728d2e30dfec006d8cd6fee53",
        "address": "bcrt1q7fm5ar5eyteuw2xjuvxlasqxmrxklmjnx83cat",
        "type": "witness_v0_keyhash"
      }
    }
  ]
}

with this call

$ TX_ID="43c79b969d3e8e6cbe198f5b25e8cd03120372eab26578f486bc6258b8677a57"
$ PSBT=$(bitcoin-cli createpsbt "[{\"txid\":\"${TX_ID}\",\"vout\":0}]" "[{\"bcrt1q2xfvunp3hnl4yc2tn99epl27xqmxnxpp9st8ad\":0.5},{\"bcrt1qvlpe3vvtr7jxgkp5yyqsum795w03n8236uujql\":0.49}]")

$ lncli wallet psbt finalize $PSBT

produce this error for lnd?

[lncli] rpc error: code = Unknown desc = error finalizing PSBT: invalid PSBT, input with index 0 missing utxo information

Context

I was originally trying this on lnd 15 and running into the same errors ziggie fiest reported. And then when I bumped my docker images to 16 started getting these new errors.

Also below is the PSBT I'm trying to finalize

$ echo $PSBT
cHNidP8BAHECAAAAAVd6Z7hYYryG9HhlsupyAxIDzeglW48ZvmyOPp2Wm8dDAAAAAAD9////AoDw+gIAAAAAFgAUUZLOTDG8/1JhS5lLkP1eMDZpmCFArusCAAAAABYAFGfDmLGLH6RkWDQhAQ5vxaOfGZ1RAAAAAAAAAAA=

[guggero]

You need to add the UTXO information to each input of the PSBT. You should be able to use bitcoin-cli utxoupdatepsbt to do that.

[vindard]

This worked perfectly, thanks! I simply ran $ bitcoin-cli utxoupdatepsbt $PSBT and then used the output of that in lncli