Fix Crash due to Matrix Validation in non Matrix Pipeline

pkg/apis/pipeline/v1/pipeline_validation.go

@@ -779,8 +779,15 @@ func validateGraph(tasks []PipelineTask) (errs *apis.FieldError) {
 }
 
 func validateMatrix(ctx context.Context, tasks []PipelineTask) (errs *apis.FieldError) {
+	hasMatrix := false
 	for idx, task := range tasks {
-		errs = errs.Also(task.validateMatrix(ctx).ViaIndex(idx))
+		if task.IsMatrixed() {
+			errs = errs.Also(task.validateMatrix(ctx).ViaIndex(idx))
+			hasMatrix = true
+		}
+	}
+	if !hasMatrix {
+		return errs
 	}
 	errs = errs.Also(validateTaskResultsFromMatrixedPipelineTasksConsumed(tasks))
 	return errs
@@ -812,6 +819,9 @@ func validateMatrixedPipelineTaskConsumed(expressions []string, taskMapping map[
 	for _, expression := range expressions {
 		// ie. "tasks.<pipelineTaskName>.results.<resultName>[*]"
 		subExpressions := strings.Split(expression, ".")
+		if len(subExpressions) < 2 {
+			continue
+		}
 		pipelineTask := subExpressions[1] // pipelineTaskName
 		taskConsumed := taskMapping[pipelineTask]
 		if taskConsumed.IsMatrixed() {

test/e2e-tests-upgrade.sh

@@ -82,14 +82,30 @@ header "Create resources at previous release version"
 kubectl create namespace upgrade
 trap "kubectl delete namespace upgrade" EXIT
 kubectl create -f ./test/upgrade/simpleResources.yaml || fail_test
+kubectl create -f ./test/upgrade/resultRefResources.yaml || fail_test
 
 # Upgrade to the current release.
 header "Upgrade to the current release of Tekton pipeline"
 install_pipeline_crd
 
+initRestartCount=$(kubectl get pods -o=jsonpath='{.items[?(@.metadata.labels.app=="tekton-pipelines-controller")].status.containerStatuses[0].restartCount}' -n ${SYSTEM_NAMESPACE})
+
 # Create runs from the Task and Pipeline resources created at the previous release version
 header "Creating TaskRuns and PipelineRuns referencing existing Tasks and Pipelines"
 kubectl create -f ./test/upgrade/simpleRuns.yaml || fail_test
+kubectl create -f ./test/upgrade/resultRefRuns.yaml || fail_test
+
+for i in $(kc get pr -o=custom-columns=NAMENAME:.metadata.name --no-headers);
+      do kubectl wait --for=jsonpath='{.status.conditions[0].reason}'=Succeeded pipelinerun $i;
+done
+
+curRestartCount=$(kubectl get pods -o=jsonpath='{.items[?(@.metadata.labels.app=="tekton-pipelines-controller")].status.containerStatuses[0].restartCount}' -n ${SYSTEM_NAMESPACE})
+
+if [ ${initRestartCount} -ne ${curRestartCount} ];
+   echo "controller restarted"
+   then fail_test;
+fi
+
 
 # Run the post-integration tests. We do not need to install the resources again, since
 # they are installed before the upgrade. We verify if they still work, after going through

test/upgrade/resultRefResources.yaml

@@ -0,0 +1,64 @@
+apiVersion: tekton.dev/v1
+kind: Task
+metadata:
+  name: add-task
+spec:
+  params:
+    - name: first
+      description: the first operand
+    - name: second
+      description: the second operand
+  results:
+    - name: sum
+      description: the sum of the first and second operand
+  steps:
+    - name: add
+      image: alpine
+      env:
+        - name: OP1
+          value: $(params.first)
+        - name: OP2
+          value: $(params.second)
+      command: ["/bin/sh", "-c"]
+      args:
+        - echo -n $((${OP1}+${OP2})) | tee $(results.sum.path);
+---
+apiVersion: tekton.dev/v1
+kind: Pipeline
+metadata:
+  name: sum-three-pipeline
+spec:
+  params:
+    - name: first
+      description: the first operand
+    - name: second
+      description: the second operand
+    - name: third
+      description: the third operand
+  tasks:
+    - name: first-add
+      taskRef:
+        name: add-task
+      params:
+        - name: first
+          value: $(params.first)
+        - name: second
+          value: $(params.second)
+    - name: second-add
+      taskRef:
+        name: add-task
+      params:
+        - name: first
+          value: $(tasks.first-add.results.sum)
+        - name: second
+          value: $(tasks.first-add.results.sum) - $(sum)
+  results:
+    - name: sum
+      description: the sum of all three operands
+      value: $(tasks.second-add.results.sum)
+    - name: partial-sum
+      description: the sum of first two operands
+      value: $(tasks.first-add.results.sum)
+    - name: all-sum
+      description: the sum of everything
+      value: $(tasks.second-add.results.sum)-$(tasks.first-add.results.sum)

test/upgrade/resultRefRuns.yaml

@@ -0,0 +1,14 @@
+apiVersion: tekton.dev/v1
+kind: PipelineRun
+metadata:
+  name: resultRefRun
+spec:
+  pipelineRef:
+    name: sum-three-pipeline
+  params:
+    - name: first
+      value: "2"
+    - name: second
+      value: "10"
+    - name: third
+      value: "10"