avoid data race on cache multi store lazy store loading

Author: beer-1

store/cachemulti/store.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"io"
 	"maps"
+	"sync"
 
 	"cosmossdk.io/store/tracekv"
 	"cosmossdk.io/store/types"
@@ -21,7 +22,10 @@ const storeNameCtxKey = "store_name"
 // NOTE: a Store (and MultiStores in general) should never expose the
 // keys for the substores.
 type Store struct {
-	stores map[types.StoreKey]types.CacheWrap
+	// storesMut ensures concurrent callers (e.g. ExportGenesisForModules goroutines)
+	// don't race when lazily creating substores.
+	storesMut *sync.RWMutex
+	stores    map[types.StoreKey]types.CacheWrap
 
 	traceWriter  io.Writer
 	traceContext types.TraceContext
@@ -38,6 +42,7 @@ func NewFromKVStore(
 	traceWriter io.Writer, traceContext types.TraceContext,
 ) Store {
 	cms := Store{
+		storesMut:    &sync.RWMutex{},
 		stores:       make(map[types.StoreKey]types.CacheWrap, len(stores)),
 		traceWriter:  traceWriter,
 		traceContext: traceContext,
@@ -66,6 +71,7 @@ func NewFromParent(
 	traceWriter io.Writer, traceContext types.TraceContext,
 ) Store {
 	return Store{
+		storesMut:    &sync.RWMutex{},
 		stores:       make(map[types.StoreKey]types.CacheWrap),
 		traceWriter:  traceWriter,
 		traceContext: traceContext,
@@ -126,7 +132,12 @@ func (cms Store) GetStoreType() types.StoreType {
 
 // Write calls Write on each underlying store.
 func (cms Store) Write() {
-	for _, store := range cms.stores {
+	cms.storesMut.RLock()
+	stores := make(map[types.StoreKey]types.CacheWrap, len(cms.stores))
+	maps.Copy(stores, cms.stores)
+	cms.storesMut.RUnlock()
+
+	for _, store := range stores {
 		store.Write()
 	}
 }
@@ -157,6 +168,9 @@ func (cms Store) CacheMultiStoreWithVersion(_ int64) (types.CacheMultiStore, err
 }
 
 func (cms Store) getCacheWrapper(key types.StoreKey) types.CacheWrapper {
+	cms.storesMut.Lock()
+	defer cms.storesMut.Unlock()
+
 	store, ok := cms.stores[key]
 	if !ok && cms.parentStore != nil {
 		// load on demand

store/cachemulti/store_test.go

@@ -2,6 +2,7 @@ package cachemulti
 
 import (
 	"fmt"
+	"sync"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -12,7 +13,7 @@ import (
 func TestStoreGetKVStore(t *testing.T) {
 	require := require.New(t)
 
-	s := Store{stores: map[types.StoreKey]types.CacheWrap{}}
+	s := Store{storesMut: &sync.RWMutex{}, stores: map[types.StoreKey]types.CacheWrap{}}
 	key := types.NewKVStoreKey("abc")
 	errMsg := fmt.Sprintf("kv store with key %v has not been registered in stores", key)
 

tests/go.mod

@@ -239,6 +239,7 @@ require (
 replace (
 	// We always want to test against the latest version of the simapp.
 	cosmossdk.io/simapp => ../simapp
+	cosmossdk.io/store => ../store
 	github.com/99designs/keyring => github.com/cosmos/keyring v1.2.0
 	// We always want to test against the latest version of the SDK.
 	github.com/cosmos/cosmos-sdk => ../.

tests/go.sum

@@ -40,8 +40,6 @@ cosmossdk.io/math v1.5.3 h1:WH6tu6Z3AUCeHbeOSHg2mt9rnoiUWVWaQ2t6Gkll96U=
 cosmossdk.io/math v1.5.3/go.mod h1:uqcZv7vexnhMFJF+6zh9EWdm/+Ylyln34IvPnBauPCQ=
 cosmossdk.io/schema v1.1.0 h1:mmpuz3dzouCoyjjcMcA/xHBEmMChN+EHh8EHxHRHhzE=
 cosmossdk.io/schema v1.1.0/go.mod h1:Gb7pqO+tpR+jLW5qDcNOSv0KtppYs7881kfzakguhhI=
-cosmossdk.io/store v1.3.0-beta.0 h1:jwJvAQkMsCY9xJHU/nz7yOo1WnNRvcI/9yLRSgZoFTk=
-cosmossdk.io/store v1.3.0-beta.0/go.mod h1:CMz9JQGEA8eRcZv2pK07NgEbL4NEb9wVgzWK4tNQaPg=
 cosmossdk.io/x/tx v0.14.0 h1:hB3O25kIcyDW/7kMTLMaO8Ripj3yqs5imceVd6c/heA=
 cosmossdk.io/x/tx v0.14.0/go.mod h1:Tn30rSRA1PRfdGB3Yz55W4Sn6EIutr9xtMKSHij+9PM=
 dmitri.shuralyov.com/gpu/mtl v0.0.0-20190408044501-666a987793e9/go.mod h1:H6x//7gZCb22OMCxBHrMx7a5I7Hp++hsVxbQ4BYO7hU=