[cherry-pick: release-v0.46.x] fix: prevent unbounded tar layer allocation

pkg/bundle/builder_test.go

@@ -131,14 +131,13 @@ func TestBuildTektonBundle(t *testing.T) {
 
 	// If the user bundled this up as a tar file then we need to untar it.
 	treader := tar.NewReader(rc)
-	header, err := treader.Next()
-	if err != nil {
+	if _, err := treader.Next(); err != nil {
 		t.Errorf("layer is not a tarball")
 	}
 
-	contents := make([]byte, header.Size)
-	if _, err := treader.Read(contents); err != nil && err != io.EOF {
-		// We only allow 1 resource per layer so this tar bundle should have one and only one file.
+	limited := io.LimitReader(treader, MaxLayerSize+1)
+	contents, err := io.ReadAll(limited)
+	if err != nil && err != io.EOF {
 		t.Errorf("failed to read tar bundle: %v", err)
 	}
 

pkg/bundle/reader.go

@@ -15,6 +15,9 @@ import (
 // Tekton bundle. The `version`, `kind`, and `name` fields map 1:1 with the same named fields in the Tekton Bundle spec.
 type ObjectVisitor func(version, kind, name string, element runtime.Object, raw []byte)
 
+// setting a limit reader to avoid reading more than 1.5 MiB from the layer
+const MaxLayerSize = 15 << 20 / 10
+
 // List will call visitor for every single layer in the img.
 func List(img v1.Image, visitor ObjectVisitor) error {
 	manifest, err := img.Manifest()
@@ -110,15 +113,16 @@ func readTarLayer(l v1.Layer) ([]byte, error) {
 
 	// If the user bundled this up as a tar file then we need to untar it.
 	treader := tar.NewReader(rc)
-	header, err := treader.Next()
-	if err != nil {
+	if _, err := treader.Next(); err != nil {
 		return nil, fmt.Errorf("layer is not a tarball")
 	}
-
-	contents := make([]byte, header.Size)
-	if _, err := io.ReadFull(treader, contents); err != nil && err != io.EOF {
-		// We only allow 1 resource per layer so this tar bundle should have one and only one file.
+	limited := io.LimitReader(treader, MaxLayerSize+1)
+	contents, err := io.ReadAll(limited)
+	if err != nil {
 		return nil, fmt.Errorf("failed to read tar bundle: %w", err)
 	}
+	if int64(len(contents)) > MaxLayerSize {
+		return nil, fmt.Errorf("layer exceeds maximum allowed size of %d bytes", MaxLayerSize)
+	}
 	return contents, nil
 }

pkg/bundle/reader_test.go

@@ -4,6 +4,7 @@ import (
 	"archive/tar"
 	"bytes"
 	"fmt"
+	"io"
 	"strings"
 	"testing"
 
@@ -125,3 +126,33 @@ func TestReader(t *testing.T) {
 		t.Error(err)
 	}
 }
+
+func TestReadTarLayerExceedsMaxSize(t *testing.T) {
+	oversized := make([]byte, MaxLayerSize+1)
+
+	var buf bytes.Buffer
+	tw := tar.NewWriter(&buf)
+	_ = tw.WriteHeader(&tar.Header{
+		Name: "oversizedtask.yaml",
+		Size: int64(len(oversized)),
+	})
+	_, _ = tw.Write(oversized)
+	_ = tw.Close()
+
+	// Wrap as a fake v1.Layer via tarball.FromOpener
+	opener := func() (io.ReadCloser, error) {
+		return io.NopCloser(bytes.NewReader(buf.Bytes())), nil
+	}
+	layer, err := tarball.LayerFromOpener(opener)
+	if err != nil {
+		t.Fatalf("failed to create layer: %v", err)
+	}
+
+	_, err = readTarLayer(layer)
+	if err == nil {
+		t.Fatal("expected error for oversized layer, got nil")
+	}
+	if !strings.Contains(err.Error(), "layer exceeds maximum allowed size") {
+		t.Errorf("unexpected error message: %v", err)
+	}
+}

pkg/cmd/bundle/push_test.go

@@ -245,15 +245,13 @@ func readTarLayer(t *testing.T, layer v1.Layer) string {
 
 	// If the user bundled this up as a tar file then we need to untar it.
 	treader := tar.NewReader(rc)
-	header, err := treader.Next()
-	if err != nil {
+	if _, err := treader.Next(); err != nil {
 		t.Errorf("layer is not a tarball")
-
 	}
 
-	contents := make([]byte, header.Size)
-	if _, err := treader.Read(contents); err != nil && err != io.EOF {
-		// We only allow 1 resource per layer so this tar bundle should have one and only one file.
+	limited := io.LimitReader(treader, bundle.MaxLayerSize+1)
+	contents, err := io.ReadAll(limited)
+	if err != nil && err != io.EOF {
 		t.Errorf("failed to read tar bundle: %v", err)
 	}
 	return string(contents)