Requesting a partial signature on a vanilla Taproot funded PSBT results in panic

alexbosworth commented 2 years ago

Background

When calling SignPsbt on a PSBT that was created referencing a P2TR UTXO but absent Taproot specific fields, LND will terminate with ?panic: runtime error: invalid memory address or nil pointer dereference

Your environment

lnd v0.15.0-beta.rc2 (docker tag)

Steps to reproduce

Create a wallet with a P2TR UTXO
Create a PSBT referencing this UTXO, but absent the taproot specific bip32 derivation fields etc
Call SignPsbt on that PSBT

Expected behavior

An error returned over the API

Actual behavior

LND termination

?panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0x2f4b48]

goroutine 1224 [running]:
github.com/btcsuite/btcd/txscript.NewTxSigHashes(0x4002338080, {0x19be168, 0x4000120ee8})
    github.com/btcsuite/btcd@v0.22.0-beta.0.20220413172512-bf64c8bdbbbf/txscript/hashcache.go:243 +0x158
github.com/lightningnetwork/lnd/lnwallet/btcwallet.(*BtcWallet).SignPsbt(0x0?, 0x400230f9a0)
    github.com/lightningnetwork/lnd/lnwallet/btcwallet/psbt.go:115 +0x64
github.com/lightningnetwork/lnd/lnrpc/walletrpc.(*WalletKit).SignPsbt(0x400055a4c8, {0x15c4660?, 0x0?}, 0x40014e5f00)
    github.com/lightningnetwork/lnd/lnrpc/walletrpc/walletkit_server.go:1240 +0x1f8
github.com/lightningnetwork/lnd/lnrpc/walletrpc._WalletKit_SignPsbt_Handler.func1({0x19d3c20, 0x4002303f50}, {0x1461500?, 0x40014e5f00})
    github.com/lightningnetwork/lnd/lnrpc/walletrpc/walletkit_grpc.pb.go:993 +0x78
    ithub.com/grpc-ecosystem/go-grpc-prometheus.(*ServerMetrics).UnaryServerInterceptor.func1({0x19d3c20, 0x4002303f50}, {0x1461500, 0x40014e5f00}, 0x4000434bc0?, 0x400277b998)
    github.com/grpc-ecosystem/go-grpc-prometheus@v1.2.0/server_metrics.go:107 +0x78
github.com/grpc-ecosystem/go-grpc-middleware.ChainUnaryServer.func1.1.1({0x19d3c20?, 0x4002303f50?}, {0x1461500?, 0x40014e5f00?})
    github.com/grpc-ecosystem/go-grpc-middleware@v1.3.0/chain.go:25 +0x40
github.com/lightningnetwork/lnd/rpcperms.(*InterceptorChain).middlewareUnaryServerInterceptor.func1({0x19d3c20, 0x4002303f50}, {0x1461500, 0x40014e5f00}, 0x40002a8200, 0x40002a8220)
    github.com/lightningnetwork/lnd/rpcperms/interceptor.go:789 +0x1a0
github.com/grpc-ecosystem/go-grpc-middleware.ChainUnaryServer.func1.1.1({0x19d3c20?, 0x4002303f50?}, {0x1461500?, 0x40014e5f00?})
    github.com/grpc-ecosystem/go-grpc-middleware@v1.3.0/chain.go:25 +0x40
github.com/lightningnetwork/lnd/rpcperms.(*InterceptorChain).MacaroonUnaryServerInterceptor.func1({0x19d3c20, 0x4002303f50}, {0x1461500, 0x40014e5f00}, 0x40014ab320?, 0x40002a8240)
    github.com/lightningnetwork/lnd/rpcperms/interceptor.go:663 +0x94
github.com/grpc-ecosystem/go-grpc-middleware.ChainUnaryServer.func1.1.1({0x19d3c20?, 0x4002303f50?}, {0x1461500?, 0x40014e5f00?})
    github.com/grpc-ecosystem/go-grpc-middleware@v1.3.0/chain.go:25 +0x40
github.com/lightningnetwork/lnd/rpcperms.(*InterceptorChain).rpcStateUnaryServerInterceptor.func1({0x19d3c20, 0x4002303f50}, {0x1461500, 0x40014e5f00}, 0x400149f998?, 0x40002a8260)
    github.com/lightningnetwork/lnd/rpcperms/interceptor.go:753 +0x88
github.com/grpc-ecosystem/go-grpc-middleware.ChainUnaryServer.func1.1.1({0x19d3c20?, 0x4002303f50?}, {0x1461500?, 0x40014e5f00?})
    github.com/grpc-ecosystem/go-grpc-middleware@v1.3.0/chain.go:25 +0x40
github.com/lightningnetwork/lnd/rpcperms.errorLogUnaryServerInterceptor.func1({0x19d3c20?, 0x4002303f50?}, {0x1461500?, 0x40014e5f00?}, 0x40002a8200, 0x40002a8200?)
    github.com/lightningnetwork/lnd/rpcperms/interceptor.go:579 +0x4c
github.com/grpc-ecosystem/go-grpc-middleware.ChainUnaryServer.func1.1.1({0x19d3c20?, 0x4002303f50?}, {0x1461500?, 0x40014e5f00?})
    github.com/grpc-ecosystem/go-grpc-middleware@v1.3.0/chain.go:25 +0x40
github.com/grpc-ecosystem/go-grpc-middleware.ChainUnaryServer.func1({0x19d3c20, 0x4002303f50}?, {0x1461500, 0x40014e5f00}, 0x4002a2fab8?, 0x78cd30?)
    github.com/grpc-ecosystem/go-grpc-middleware@v1.3.0/chain.go:34 +0xbc
github.com/lightningnetwork/lnd/lnrpc/walletrpc._WalletKit_SignPsbt_Handler({0x15c4660?, 0x400011d730}, {0x19d3c20, 0x4002303f50}, 0x400087bda0, 0x40002dbf50)
    github.com/lightningnetwork/lnd/lnrpc/walletrpc/walletkit_grpc.pb.go:995 +0x138
google.golang.org/grpc.(*Server).processUnaryRPC(0x4000174c40, {0x19e1008, 0x400056c180}, 0x4002316120, 0x40002f26f0, 0x2707530, 0x0)
    google.golang.org/grpc@v1.38.0/server.go:1286 +0xad4
google.golang.org/grpc.(*Server).handleStream(0x4000174c40, {0x19e1008, 0x400056c180}, 0x4002316120, 0x0)
    google.golang.org/grpc@v1.38.0/server.go:1609 +0x854
google.golang.org/grpc.(*Server).serveStreams.func1.2()
    google.golang.org/grpc@v1.38.0/server.go:934 +0x88
created by google.golang.org/grpc.(*Server).serveStreams.func1
    google.golang.org/grpc@v1.38.0/server.go:932 +0x29c

Roasbeef commented 2 years ago

Looks like we might be missing a check in this routine: https://github.com/lightningnetwork/lnd/blob/master/lnwallet/btcwallet/psbt.go#L221

Roasbeef commented 2 years ago

So it's panicing here: https://github.com/btcsuite/btcd/blob/master/txscript/hashcache.go#L239-L244 because wallet.PsbtPrevOutputFetcher is missing information it needs to populate things.

Roasbeef commented 2 years ago

on a PSBT that was created referencing a P2TR UTXO but absent Taproot specific fields, LND will terminate with

Is it that the taproot specific derivation info wasn't added, or that the base input UTXO fields weren't added?

alexbosworth commented 2 years ago

I think it could be without the base UTXO fields, I have to take another look at how I structured it, I think I tried it with the old bip32 derivation fields though and I need to convert them to the new taproot bip32 derivation fields

lightningnetwork / lnd