core/state/snapshot: fix data race in diff layer (ethereum#22540)

Author: fxfactorial

core/state/snapshot/difflayer.go

@@ -296,13 +296,17 @@ func (dl *diffLayer) AccountRLP(hash common.Hash) ([]byte, error) {
 	if !hit {
 		hit = dl.diffed.Contains(destructBloomHasher(hash))
 	}
+	var origin *diskLayer
+	if !hit {
+		origin = dl.origin // extract origin while holding the lock
+	}
 	dl.lock.RUnlock()
 
 	// If the bloom filter misses, don't even bother with traversing the memory
 	// diff layers, reach straight into the bottom persistent disk layer
-	if !hit {
+	if origin != nil {
 		snapshotBloomAccountMissMeter.Mark(1)
-		return dl.origin.AccountRLP(hash)
+		return origin.AccountRLP(hash)
 	}
 	// The bloom filter hit, start poking in the internal maps
 	return dl.accountRLP(hash, 0)
@@ -358,13 +362,17 @@ func (dl *diffLayer) Storage(accountHash, storageHash common.Hash) ([]byte, erro
 	if !hit {
 		hit = dl.diffed.Contains(destructBloomHasher(accountHash))
 	}
+	var origin *diskLayer
+	if !hit {
+		origin = dl.origin // extract origin while holding the lock
+	}
 	dl.lock.RUnlock()
 
 	// If the bloom filter misses, don't even bother with traversing the memory
 	// diff layers, reach straight into the bottom persistent disk layer
-	if !hit {
+	if origin != nil {
 		snapshotBloomStorageMissMeter.Mark(1)
-		return dl.origin.Storage(accountHash, storageHash)
+		return origin.Storage(accountHash, storageHash)
 	}
 	// The bloom filter hit, start poking in the internal maps
 	return dl.storage(accountHash, storageHash, 0)