Stored XSS vulnerability in Jenkins upstream cause

@@ -29,20 +29,20 @@ THE SOFTWARE.
         <j:when test="${it.upstreamUrl!=null and app.getItemByFullName(it.upstreamProject)!=null}">
           <j:choose>
             <j:when test="${app.getItemByFullName(it.upstreamProject).getBuildByNumber(it.upstreamBuild)!=null}">
-              <j:out value="${%started_by_project(app.getItemByFullName(it.upstreamProject).fullDisplayName,it.upstreamBuild.toString(),it.upstreamUrl,rootURL)}"/>
+              ${%started_by_project(app.getItemByFullName(it.upstreamProject).fullDisplayName,it.upstreamBuild.toString(),it.upstreamUrl,rootURL)}
             </j:when>
             <j:otherwise>
-              <j:out value="${%started_by_project_with_deleted_build(app.getItemByFullName(it.upstreamProject).fullDisplayName,it.upstreamBuild.toString(),it.upstreamUrl,rootURL)}"/>
+              ${%started_by_project_with_deleted_build(app.getItemByFullName(it.upstreamProject).fullDisplayName,it.upstreamBuild.toString(),it.upstreamUrl,rootURL)}
             </j:otherwise>
           </j:choose>
         </j:when>
         <j:otherwise>
-          <j:out value="${it.shortDescription}"/>
+          ${it.shortDescription}
         </j:otherwise>
       </j:choose>
  
         <j:if test="${!it.upstreamCauses.isEmpty()}">
-            <br /><j:out value="${%caused_by}" />
+            <br />${%caused_by}
             <ul>
 	        <j:forEach var="c" items="${it.upstreamCauses}">
 	          <li><st:include page="description.jelly" it="${c}" /></li>

@@ -0,0 +1,167 @@
+/*
+ * The MIT License
+ *
+ * Copyright (c) 2020 CloudBees, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package hudson.model;
+ 
+import hudson.tasks.BuildTrigger;
+import jenkins.model.Jenkins;
+import org.junit.Rule;
+import org.junit.Test;
+import org.jvnet.hudson.test.Issue;
+import org.jvnet.hudson.test.JenkinsRule;
+import org.jvnet.hudson.test.TestExtension;
+ 
+import java.io.IOException;
+import java.util.concurrent.atomic.AtomicBoolean;
+ 
+import static org.junit.Assert.assertFalse;
+ 
+public class UpstreamCauseSEC1901Test {
+ 
+    @Rule
+    public JenkinsRule j = new JenkinsRule();
+ 
+    @Test
+    @Issue("SECURITY-1901")
+    public void preventXssInUpstreamDisplayName() throws Exception {
+        j.jenkins.setQuietPeriod(0);
+        FreeStyleProject up = j.createFreeStyleProject("up");
+        up.setDisplayName("Up<script>alert(123)</script>Project");
+ 
+        FreeStyleProject down = j.createFreeStyleProject("down");
+ 
+        up.getPublishersList().add(new BuildTrigger(down.getFullName(), false));
+ 
+        j.jenkins.rebuildDependencyGraph();
+ 
+        j.buildAndAssertSuccess(up);
+ 
+        FreeStyleBuild downBuild = this.waitForDownBuild(down);
+ 
+        ensureXssIsPrevented(downBuild);
+    }
+ 
+    @Test
+    @Issue("SECURITY-1901")
+    public void preventXssInUpstreamDisplayName_deleted() throws Exception {
+        j.jenkins.setQuietPeriod(0);
+        FreeStyleProject up = j.createFreeStyleProject("up");
+        up.setDisplayName("Up<script>alert(123)</script>Project");
+ 
+        FreeStyleProject down = j.createFreeStyleProject("down");
+ 
+        up.getPublishersList().add(new BuildTrigger(down.getFullName(), false));
+ 
+        j.jenkins.rebuildDependencyGraph();
+ 
+        FreeStyleBuild upBuild = j.buildAndAssertSuccess(up);
+ 
+        FreeStyleBuild downBuild = this.waitForDownBuild(down);
+ 
+        // that will display a different part
+        upBuild.delete();
+ 
+        ensureXssIsPrevented(downBuild);
+    }
+ 
+    @Test
+    @Issue("SECURITY-1901")
+    public void preventXssInUpstreamShortDescription() throws Exception {
+        FullNameChangingProject up = j.createProject(FullNameChangingProject.class, "up");
+ 
+        FreeStyleProject down = j.createFreeStyleProject("down");
+ 
+        CustomBuild upBuild = j.buildAndAssertSuccess(up);
+ 
+        up.setVirtualName("Up<script>alert(123)</script>Project");
+        j.assertBuildStatusSuccess(down.scheduleBuild2(0, new Cause.UpstreamCause(upBuild)));
+        up.setVirtualName(null);
+ 
+        FreeStyleBuild downBuild = this.waitForDownBuild(down);
+ 
+        ensureXssIsPrevented(downBuild);
+    }
+    
+    private void ensureXssIsPrevented(FreeStyleBuild downBuild) throws Exception {
+        AtomicBoolean alertCalled = new AtomicBoolean(false);
+ 
+        JenkinsRule.WebClient wc = j.createWebClient();
+        wc.setAlertHandler((page, s) -> alertCalled.set(true));
+        wc.goTo(downBuild.getUrl());
+ 
+        assertFalse("XSS not prevented", alertCalled.get());
+    }
+ 
+    private <B extends Build<?, B>> B waitForDownBuild(Project<?, B> down) throws Exception {
+        j.waitUntilNoActivity();
+        B result = down.getBuilds().getLastBuild();
+ 
+        return result;
+    }
+ 
+    public static class CustomBuild extends Build<FullNameChangingProject, CustomBuild> {
+        public CustomBuild(FullNameChangingProject job) throws IOException {
+            super(job);
+        }
+    }
+ 
+    static class FullNameChangingProject extends Project<FullNameChangingProject, CustomBuild> implements TopLevelItem {
+        private volatile String virtualName;
+ 
+        public FullNameChangingProject(ItemGroup parent, String name) {
+            super(parent, name);
+        }
+ 
+        public void setVirtualName(String virtualName) {
+            this.virtualName = virtualName;
+        }
+ 
+        @Override
+        public String getName() {
+            if (virtualName != null) {
+                return virtualName;
+            } else {
+                return super.getName();
+            }
+        }
+ 
+        @Override
+        protected Class<CustomBuild> getBuildClass() {
+            return CustomBuild.class;
+        }
+ 
+        @Override
+        public TopLevelItemDescriptor getDescriptor() {
+            return (FreeStyleProject.DescriptorImpl) Jenkins.get().getDescriptorOrDie(getClass());
+        }
+ 
+        @TestExtension
+        public static class DescriptorImpl extends AbstractProjectDescriptor {
+ 
+            @Override
+            public FullNameChangingProject newInstance(ItemGroup parent, String name) {
+                return new FullNameChangingProject(parent, name);
+            }
+        }
+    }
+}