fix: nested iterator on cache store (cosmos#14798)

CHANGELOG.md

@@ -40,6 +40,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### Bug Fixes
 
+- (store) [#14798](https://github.com/cosmos/cosmos-sdk/pull/14798) Copy btree to avoid the problem of modify while iteration.
 - (cli) [#14799](https://github.com/cosmos/cosmos-sdk/pull/14799) Fix Evidence CLI query flag parsing (backport #13458)
 
 ## [v0.46.8](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.46.8) - 2022-01-23

store/cachekv/internal/btree.go

@@ -63,6 +63,12 @@ func (bt *BTree) ReverseIterator(start, end []byte) (*memIterator, error) {
 	return NewMemIterator(start, end, bt, make(map[string]struct{}), false), nil
 }
 
+func (bt *BTree) Copy() *BTree {
+	return &BTree{
+		tree: *bt.tree.Copy(),
+	}
+}
+
 // item is a btree item with byte slices as keys and values
 type item struct {
 	key   []byte

store/cachekv/store.go

@@ -226,7 +226,7 @@ func (store *Store) iterator(start, end []byte, ascending bool) types.Iterator {
 	}
 
 	store.dirtyItems(start, end)
-	cache = internal.NewMemIterator(start, end, store.sortedCache, store.deleted, ascending)
+	cache = internal.NewMemIterator(start, end, store.sortedCache.Copy(), store.deleted, ascending)
 
 	return internal.NewCacheMergeIterator(parent, cache, ascending)
 }