Merge pull request #7471 from bacongobbler/backport-7443

fix(engine): allow limited recursion in templates

pkg/engine/engine.go

@@ -32,6 +32,8 @@ import (
 	"k8s.io/helm/pkg/proto/hapi/chart"
 )
 
+const recursionMaxNums = 1000
+
 // Engine is an implementation of 'cmd/tiller/environment'.Engine that uses Go templates.
 type Engine struct {
 	// FuncMap contains the template functions that will be passed to each
@@ -145,21 +147,23 @@ func (e *Engine) alterFuncMap(t *template.Template, referenceTpls map[string]ren
 		funcMap[k] = v
 	}
 
-	includedNames := make([]string, 0)
+	includedNames := make(map[string]int)
 
 	// Add the 'include' function here so we can close over t.
 	funcMap["include"] = func(name string, data interface{}) (string, error) {
 		buf := bytes.NewBuffer(nil)
-		for _, n := range includedNames {
-			if n == name {
-				return "", errors.Wrapf(fmt.Errorf("unable to excute template"), "rendering template has a nested reference name: %s", name)
+		if v, ok := includedNames[name]; ok {
+			if v > recursionMaxNums {
+				return "", errors.Wrapf(fmt.Errorf("unable to execute template"), "rendering template has a nested reference name: %s", name)
 			}
+			includedNames[name]++
+		} else {
+			includedNames[name] = 1
 		}
-		includedNames = append(includedNames, name)
 		if err := t.ExecuteTemplate(buf, name, data); err != nil {
 			return "", err
 		}
-		includedNames = includedNames[:len(includedNames)-1]
+		includedNames[name]--
 		return buf.String(), nil
 	}
 

pkg/engine/engine_test.go

@@ -18,6 +18,7 @@ package engine
 
 import (
 	"fmt"
+	"strings"
 	"sync"
 	"testing"
 
@@ -604,3 +605,58 @@ func TestAlterFuncMap(t *testing.T) {
 	}
 
 }
+
+func TestRenderRecursionLimit(t *testing.T) {
+	// endless recursion should produce an error
+	c := &chart.Chart{
+		Metadata: &chart.Metadata{Name: "bad"},
+		Templates: []*chart.Template{
+			{Name: "templates/base", Data: []byte(`{{include "recursion" . }}`)},
+			{Name: "templates/recursion", Data: []byte(`{{define "recursion"}}{{include "recursion" . }}{{end}}`)},
+		},
+	}
+	v := chartutil.Values{
+		"Values": "",
+		"Chart":  c.Metadata,
+		"Release": chartutil.Values{
+			"Name": "TestRelease",
+		},
+	}
+	expectErr := "rendering template has a nested reference name: recursion: unable to execute template"
+
+	e := New()
+	_, err := e.Render(c, v)
+	if err == nil || !strings.HasSuffix(err.Error(), expectErr) {
+		t.Errorf("Expected err with suffix: %s", expectErr)
+	}
+
+	// calling the same function many times is ok
+	times := 4000
+	phrase := "All work and no play makes Jack a dull boy"
+	printFunc := `{{define "overlook"}}{{printf "` + phrase + `\n"}}{{end}}`
+	var repeatedIncl string
+	for i := 0; i < times; i++ {
+		repeatedIncl += `{{include "overlook" . }}`
+	}
+
+	d := &chart.Chart{
+		Metadata: &chart.Metadata{Name: "overlook"},
+		Templates: []*chart.Template{
+			{Name: "templates/quote", Data: []byte(repeatedIncl)},
+			{Name: "templates/_function", Data: []byte(printFunc)},
+		},
+	}
+
+	out, err := e.Render(d, v)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var expect string
+	for i := 0; i < times; i++ {
+		expect += phrase + "\n"
+	}
+	if got := out["overlook/templates/quote"]; got != expect {
+		t.Errorf("Expected %q, got %q (%v)", expect, got, out)
+	}
+}