From ac8ce8270171da3f0d73c06a437fd78ea9461dc1 Mon Sep 17 00:00:00 2001
From: yyforyongyu <yong2452@gmail.com>
Date: Mon, 1 Jul 2024 18:14:10 +0800
Subject: [PATCH] contractcourt: fix race access to `c.activeResolvers`

---
 contractcourt/channel_arbitrator.go | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/contractcourt/channel_arbitrator.go b/contractcourt/channel_arbitrator.go
index 1d2268afe03..86418a6414a 100644
--- a/contractcourt/channel_arbitrator.go
+++ b/contractcourt/channel_arbitrator.go
@@ -811,11 +811,8 @@ func (c *ChannelArbitrator) relaunchResolvers(commitSet *CommitSet,
 
 // Report returns htlc reports for the active resolvers.
 func (c *ChannelArbitrator) Report() []*ContractReport {
-	c.activeResolversLock.RLock()
-	defer c.activeResolversLock.RUnlock()
-
 	var reports []*ContractReport
-	for _, resolver := range c.activeResolvers {
+	for _, resolver := range c.resolvers() {
 		r, ok := resolver.(reportingContractResolver)
 		if !ok {
 			continue
@@ -1569,6 +1566,7 @@ func (c *ChannelArbitrator) findCommitmentDeadlineAndValue(heightHint uint32,
 // resolveContracts updates the activeResolvers list and starts to resolve each
 // contract concurrently, and launches them.
 func (c *ChannelArbitrator) resolveContracts(resolvers []ContractResolver) {
+	// Update the active contract resolvers.
 	c.activeResolversLock.Lock()
 	c.activeResolvers = resolvers
 	c.activeResolversLock.Unlock()
@@ -1576,7 +1574,7 @@ func (c *ChannelArbitrator) resolveContracts(resolvers []ContractResolver) {
 	// Launch all resolvers.
 	c.launchResolvers()
 
-	for _, contract := range resolvers {
+	for _, contract := range c.resolvers() {
 		c.wg.Add(1)
 		go c.resolveContract(contract)
 	}
@@ -1584,11 +1582,7 @@ func (c *ChannelArbitrator) resolveContracts(resolvers []ContractResolver) {
 
 // launchResolvers launches all the active resolvers.
 func (c *ChannelArbitrator) launchResolvers() {
-	c.activeResolversLock.Lock()
-	resolvers := c.activeResolvers
-	c.activeResolversLock.Unlock()
-
-	for _, contract := range resolvers {
+	for _, contract := range c.resolvers() {
 		// If the contract is already resolved, there's no need to
 		// launch it again.
 		if contract.IsResolved() {
@@ -3426,3 +3420,14 @@ func (c *ChannelArbitrator) abandonForwards(htlcs fn.Set[uint64]) error {
 
 	return nil
 }
+
+// resolvers returns a copy of the active resolvers.
+func (c *ChannelArbitrator) resolvers() []ContractResolver {
+	c.activeResolversLock.Lock()
+	defer c.activeResolversLock.Unlock()
+
+	resolvers := make([]ContractResolver, 0, len(c.activeResolvers))
+	resolvers = append(resolvers, c.activeResolvers...)
+
+	return resolvers
+}