fix(gnovm): protect TypedValue stringer against deep recursivity (#3790)

The protectedStringer is improved by limiting the successive number of
nested calls when constructing the string representation of a deeply
recursive value.

Fixes #3471.

---------

Co-authored-by: ltzmaxwell <ltz.maxwell@gmail.com>

gnovm/pkg/gnolang/values_string.go

@@ -12,11 +12,17 @@ type protectedStringer interface {
 	ProtectedString(*seenValues) string
 }
 
-// This indicates the maximum anticipated depth of the stack when printing a Value type.
-const defaultSeenValuesSize = 32
+const (
+	// defaultSeenValuesSize indicates the maximum anticipated depth of the stack when printing a Value type.
+	defaultSeenValuesSize = 32
+
+	// nestedLimit indicates the maximum nested level when printing a deeply recursive value.
+	nestedLimit = 10
+)
 
 type seenValues struct {
 	values []Value
+	nc     int // nested counter, to limit recursivity
 }
 
 func (sv *seenValues) Put(v Value) {
@@ -46,7 +52,7 @@ func (sv *seenValues) Pop() {
 }
 
 func newSeenValues() *seenValues {
-	return &seenValues{values: make([]Value, 0, defaultSeenValuesSize)}
+	return &seenValues{values: make([]Value, 0, defaultSeenValuesSize), nc: nestedLimit}
 }
 
 func (v StringValue) String() string {
@@ -74,6 +80,10 @@ func (av *ArrayValue) ProtectedString(seen *seenValues) string {
 		return fmt.Sprintf("%p", av)
 	}
 
+	seen.nc--
+	if seen.nc < 0 {
+		return "..."
+	}
 	seen.Put(av)
 	defer seen.Pop()
 

gnovm/tests/files/recurse1.gno

@@ -0,0 +1,12 @@
+package main
+
+func main() {
+	var x interface{}
+	for i := 0; i < 10000; i++ {
+		x = [1]interface{}{x}
+	}
+	println(x)
+}
+
+// Output:
+// array[(array[(array[(array[(array[(array[(array[(array[(array[(array[(... [1]interface{})] [1]interface{})] [1]interface{})] [1]interface{})] [1]interface{})] [1]interface{})] [1]interface{})] [1]interface{})] [1]interface{})] [1]interface{})]