[bug]: `panic: runtime error` resuming HTLC attempt

[djkazic]

Background

On LND 0.19.0 rc2 during startup this panic was observed:

2025-04-08 18:51:38.941 [INF] CRTR: Resuming HTLC attempt 35020 for payment 53a3012ec149f3a478e13a7e16617fca658f87e80f26c8b5ffa7091be9ce34a6
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x19c407e]
goroutine 1191 [running]:
github.com/lightningnetwork/lnd/channeldb.(*HTLCAttemptInfo).attachOnionBlobAndCircuit(0xc00775ca08)
    github.com/lightningnetwork/lnd/channeldb/mp_payment.go:123 +0x1e
github.com/lightningnetwork/lnd/channeldb.(*HTLCAttemptInfo).Circuit(...)
    github.com/lightningnetwork/lnd/channeldb/mp_payment.go:111
github.com/lightningnetwork/lnd/routing.(*paymentLifecycle).collectResult(0xc00509a180, 0xc00775ca08)
    github.com/lightningnetwork/lnd/routing/payment_lifecycle.go:508 +0x11a
github.com/lightningnetwork/lnd/routing.(*paymentLifecycle).collectResultAsync.func1()
    github.com/lightningnetwork/lnd/routing/payment_lifecycle.go:464 +0x31
created by github.com/lightningnetwork/lnd/routing.(*paymentLifecycle).collectResultAsync in goroutine 1068
    github.com/lightningnetwork/lnd/routing/payment_lifecycle.go:463 +0x12a

Line for ref:

    onionBlob, circuit, err := GenerateSphinxPacket(
        &h.Route, h.Hash[:], h.SessionKey(),
    )

Based on the valid memory address, h itself is not nil, so the culprit likely lies in the other fields (i.e. Route, Hash, etc.)

Your environment

• version of lnd: 0.19 rc2
• which operating system (uname -a on *Nix): Linux 5.10.225
• version of btcd, bitcoind, or other backend: bitcoind

Steps to reproduce

Upgrade instance to LND 0.19 rc2.

Expected behaviour

Start up.

Actual behaviour

Runtime panic.

[yyforyongyu]

It looks like the panic is from h.Hash[:], caused by the [:] part since Route is a concrete struct. So this only happens in 0.19 rc2?

[djkazic]

It looks like the panic is from h.Hash[:], caused by the [:] part since Route is a concrete struct. So this only happens in 0.19 rc2?

Have not tried to repro in other versions, noticed it during an upgrade from 0.18.3.