From e252572bda922e200cd8e3b508088bf87f930139 Mon Sep 17 00:00:00 2001
From: Evans Mungai <mbuevans@gmail.com>
Date: Tue, 25 Nov 2025 13:05:57 +0000
Subject: [PATCH] fix: panic in lint when CRD file is empty

Fixes #31571

The YAML decoder can return nil when a CRD file contains only
comments or whitespace. Added nil check to skip validation
in these cases. This fixes a panic in the CRD linting rule.

Signed-off-by: Evans Mungai <mbuevans@gmail.com>
---
 pkg/chart/v2/lint/rules/crds.go                     |  5 +++++
 pkg/chart/v2/lint/rules/crds_test.go                | 13 +++++++++++++
 .../v2/lint/rules/testdata/emptycrd/Chart.yaml      |  4 ++++
 .../v2/lint/rules/testdata/emptycrd/crds/empty.yaml |  3 +++
 .../lint/rules/testdata/emptycrd/templates/.gitkeep |  0
 .../v2/lint/rules/testdata/emptycrd/values.yaml     |  1 +
 6 files changed, 26 insertions(+)
 create mode 100644 pkg/chart/v2/lint/rules/testdata/emptycrd/Chart.yaml
 create mode 100644 pkg/chart/v2/lint/rules/testdata/emptycrd/crds/empty.yaml
 create mode 100644 pkg/chart/v2/lint/rules/testdata/emptycrd/templates/.gitkeep
 create mode 100644 pkg/chart/v2/lint/rules/testdata/emptycrd/values.yaml

diff --git a/pkg/chart/v2/lint/rules/crds.go b/pkg/chart/v2/lint/rules/crds.go
index 49e30192a..09ea17bd8 100644
--- a/pkg/chart/v2/lint/rules/crds.go
+++ b/pkg/chart/v2/lint/rules/crds.go
@@ -80,6 +80,11 @@ func Crds(linter *support.Linter) {
 				return
 			}
 
+			// Skip validation if yamlStruct is nil (empty document or only comments/whitespace)
+			if yamlStruct == nil {
+				continue
+			}
+
 			linter.RunLinterRule(support.ErrorSev, fpath, validateCrdAPIVersion(yamlStruct))
 			linter.RunLinterRule(support.ErrorSev, fpath, validateCrdKind(yamlStruct))
 		}
diff --git a/pkg/chart/v2/lint/rules/crds_test.go b/pkg/chart/v2/lint/rules/crds_test.go
index e644f182f..d0553dc0d 100644
--- a/pkg/chart/v2/lint/rules/crds_test.go
+++ b/pkg/chart/v2/lint/rules/crds_test.go
@@ -25,6 +25,7 @@ import (
 )
 
 const invalidCrdsDir = "./testdata/invalidcrdsdir"
+const emptyCrdDir = "./testdata/emptycrd"
 
 func TestInvalidCrdsDir(t *testing.T) {
 	linter := support.Linter{ChartDir: invalidCrdsDir}
@@ -34,3 +35,15 @@ func TestInvalidCrdsDir(t *testing.T) {
 	assert.Len(t, res, 1)
 	assert.ErrorContains(t, res[0].Err, "not a directory")
 }
+
+// TestEmptyCrd tests that empty CRD files (containing only comments/whitespace)
+// don't cause a panic when the YAML decoder returns nil.
+// This is a regression test for issue #31571.
+func TestEmptyCrd(t *testing.T) {
+	linter := support.Linter{ChartDir: emptyCrdDir}
+	Crds(&linter)
+	res := linter.Messages
+
+	// Should not panic and should have no errors
+	assert.Len(t, res, 0)
+}
diff --git a/pkg/chart/v2/lint/rules/testdata/emptycrd/Chart.yaml b/pkg/chart/v2/lint/rules/testdata/emptycrd/Chart.yaml
new file mode 100644
index 000000000..80f4faaca
--- /dev/null
+++ b/pkg/chart/v2/lint/rules/testdata/emptycrd/Chart.yaml
@@ -0,0 +1,4 @@
+apiVersion: v2
+name: emptycrd
+description: A Helm chart with empty CRD file
+version: 0.1.0
diff --git a/pkg/chart/v2/lint/rules/testdata/emptycrd/crds/empty.yaml b/pkg/chart/v2/lint/rules/testdata/emptycrd/crds/empty.yaml
new file mode 100644
index 000000000..743b6be06
--- /dev/null
+++ b/pkg/chart/v2/lint/rules/testdata/emptycrd/crds/empty.yaml
@@ -0,0 +1,3 @@
+# This file contains only comments and whitespace
+# It will decode to nil in the YAML decoder
+
diff --git a/pkg/chart/v2/lint/rules/testdata/emptycrd/templates/.gitkeep b/pkg/chart/v2/lint/rules/testdata/emptycrd/templates/.gitkeep
new file mode 100644
index 000000000..e69de29bb
diff --git a/pkg/chart/v2/lint/rules/testdata/emptycrd/values.yaml b/pkg/chart/v2/lint/rules/testdata/emptycrd/values.yaml
new file mode 100644
index 000000000..0eba2d28f
--- /dev/null
+++ b/pkg/chart/v2/lint/rules/testdata/emptycrd/values.yaml
@@ -0,0 +1 @@
+# Empty values file