Fix SlaveCommandStatistics memory leak with some commands

src/main/java/com/cloudbees/jenkins/support/impl/SlaveCommandStatistics.java

@@ -52,6 +52,8 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeMap;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 import java.util.regex.Pattern;
 import javax.annotation.Nonnegative;
 import jenkins.model.Jenkins;
@@ -65,6 +67,12 @@ public final class SlaveCommandStatistics extends Component {
 
     /*protected*/ static @Nonnegative int MAX_STATS_SIZE = 1000;
 
+    /*protected*/ static @Nonnegative int MAX_COMMAND_LENGTH =
+            Integer.getInteger(SlaveCommandStatistics.class.getName() + ".maxCommandLength", 256);
+
+    /*protected*/ static @Nonnegative int MAX_ENTRIES_PER_AGENT =
+            Integer.getInteger(SlaveCommandStatistics.class.getName() + ".maxEntriesPerAgent", 1000);
+
     private final Object statLock = new Object();
 
     @GuardedBy("statLock")
@@ -116,7 +124,10 @@ public ComponentCategory getCategory() {
         }
     }
 
-    private static final class Statistics extends Channel.Listener {
+    @VisibleForTesting
+    static final class Statistics extends Channel.Listener {
+
+        private static final Logger LOGGER = Logger.getLogger(Statistics.class.getName());
 
         /** Represents a tally of both the number of times some event occurred, and some integral metric associated with each event which should be summed. */
         private static final class CountSum {
@@ -143,29 +154,43 @@ long sum() {
 
         private final Set<File> jars = new LinkedHashSet<>();
 
+        private static void preferringOlder(Map<String, CountSum> map, String key, long value) {
+            CountSum cs = map.get(key);
+            if (cs != null) {
+                cs.tally(value);
+            } else if (map.size() < MAX_ENTRIES_PER_AGENT) {
+                cs = new CountSum();
+                cs.tally(value);
+                map.put(key, cs);
+            } else {
+                LOGGER.log(Level.FINE, () -> "Statistics map at capacity (%d), ignoring command type: %s"
+                        .formatted(MAX_ENTRIES_PER_AGENT, key));
+            }
+        }
+
         @Override
         public void onWrite(Channel channel, Command cmd, long blockSize) {
             String type = classify(cmd);
             // Synchronization probably unnecessary for tallying (since each channel processes commands sequentially),
             // but printing could happen at any time anyway.
             synchronized (writes) {
-                writes.computeIfAbsent(type, k -> new CountSum()).tally(blockSize);
+                preferringOlder(writes, type, blockSize);
             }
         }
 
         @Override
         public void onRead(Channel channel, Command cmd, long blockSize) {
             String type = classify(cmd);
             synchronized (reads) {
-                reads.computeIfAbsent(type, k -> new CountSum()).tally(blockSize);
+                preferringOlder(reads, type, blockSize);
             }
         }
 
         @Override
         public void onResponse(Channel channel, Request<?, ?> req, Response<?, ?> rsp, long totalTime) {
             String type = classify(req);
             synchronized (responses) {
-                responses.computeIfAbsent(type, k -> new CountSum()).tally(totalTime);
+                preferringOlder(responses, type, totalTime);
             }
         }
 
@@ -176,10 +201,20 @@ public void onJar(Channel channel, File jar) {
             }
         }
 
-        private static final Pattern IRRELEVANT = Pattern.compile("(@[a-f0-9]+|[(][^)]+[)])+$");
+        /** Strips brackets (content limited to 1MB), hash codes, and parentheses at the end of command strings. */
+        private static final Pattern IRRELEVANT = Pattern.compile("(\\[.{0,1048576}\\]|@[a-f0-9]+|[(][^)]+[)])+$");
 
         private static String classify(Command cmd) {
-            return IRRELEVANT.matcher(cmd.toString()).replaceFirst("");
+            return classify(cmd.toString());
+        }
+
+        @VisibleForTesting
+        static String classify(String cmdString) {
+            cmdString = IRRELEVANT.matcher(cmdString).replaceFirst("");
+            if (cmdString.length() > MAX_COMMAND_LENGTH) {
+                cmdString = cmdString.substring(0, MAX_COMMAND_LENGTH) + "...";
+            }
+            return cmdString;
         }
 
         private void print(PrintWriter out) {

src/test/java/com/cloudbees/jenkins/support/impl/SlaveCommandStatisticsClassifyTest.java

@@ -0,0 +1,121 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2025 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 com.cloudbees.jenkins.support.impl;
+
+import static com.cloudbees.jenkins.support.impl.SlaveCommandStatistics.Statistics.classify;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.*;
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+public class SlaveCommandStatisticsClassifyTest {
+
+    @Test
+    public void patternStripsEndBracketsHashAndParentheses() {
+        assertEquals(
+                "UserRequest:RemoteLaunchCallable",
+                classify("UserRequest:RemoteLaunchCallable[cmd=[docker, exec, --env, FOO=bar]]@2b194a2b"));
+
+        assertEquals("UserRequest:Callable", classify("UserRequest:Callable@1a2b3c4d[params]@5e6f7890(Context)"));
+
+        assertEquals(
+                "UserRequest:RemoteLaunchCallable",
+                classify(
+                        "UserRequest:RemoteLaunchCallable[cmd=[nohup, sh, -c, (cp script.sh script.sh.copy; sh -xe script.sh.copy)], env=[Ljava.lang.String;@284e13da]@abc123"));
+
+        assertEquals(
+                "UserRequest:UserRPCRequest:org.jenkinsci.plugins.gitclient.GitClient.addCredentials",
+                classify(
+                        "UserRequest:UserRPCRequest:org.jenkinsci.plugins.gitclient.GitClient.addCredentials[java.lang.String,com.cloudbees.plugins.credentials.common.StandardCredentials]@abc"));
+
+        assertEquals(
+                "UserRequest:hudson.FilePath$CallableWith",
+                classify("UserRequest:hudson.FilePath$CallableWith[workspace=/home/jenkins/workspace]@7f31245a"));
+
+        assertEquals(
+                "UserRequest:com.cloudbees.jenkins.support.impl.ThreadDumps$GetThreadDump",
+                classify("UserRequest:com.cloudbees.jenkins.support.impl.ThreadDumps$GetThreadDump@abc123"));
+
+        assertEquals("UserRequest:hudson.EnvVars$GetEnvVars", classify("UserRequest:hudson.EnvVars$GetEnvVars@def456"));
+
+        assertEquals(
+                "RPCRequest:hudson.FilePath.act",
+                classify(
+                        "RPCRequest:hudson.FilePath.act[hudson.FilePath$FileCallable,hudson.remoting.VirtualChannel$ACL](123)"));
+
+        assertEquals("RPCRequest:hudson.FilePath.exists", classify("RPCRequest:hudson.FilePath.exists[](456)"));
+
+        // Legacy format (pre-jenkinsci/jenkins#9921)
+        assertEquals("Response", classify("Response@456abc(hudson.remoting.Channel)"));
+        assertEquals("UserRequest:RemoteLaunchCallable", classify("UserRequest:RemoteLaunchCallable@67c6eade8"));
+
+        // Invalid hex not matched
+        assertEquals("Cmd@zebra", classify("Cmd@zebra"));
+
+        // Brackets in middle preserved ($ anchor)
+        assertEquals("Prefix[arg]:Suffix", classify("Prefix[arg]:Suffix@abc"));
+    }
+
+    @Test
+    public void hugeEnvVarsDeduplicateToSameKey() {
+        String hugeEnv = "group1,group2,group3,%s".formatted("x".repeat(12000));
+        String withHugeEnv =
+                "UserRequest:RemoteLaunchCallable[cmd=[docker, exec, --env, BUILD_USER_GROUPS=%s]]@67c6eade8"
+                        .formatted(hugeEnv);
+
+        String expected = "UserRequest:RemoteLaunchCallable";
+        assertEquals(expected, classify(withHugeEnv));
+        assertEquals(
+                expected, classify("UserRequest:RemoteLaunchCallable[cmd=[docker, --env, BUILD_NUMBER=1]]@1a2b3c4d"));
+        assertEquals(
+                expected, classify("UserRequest:RemoteLaunchCallable[cmd=[docker, --env, BUILD_NUMBER=2]]@5e6f7890"));
+        assertEquals(
+                expected,
+                classify("UserRequest:RemoteLaunchCallable[cmd=[docker, --env, TIMESTAMP=%d]]@deadbeef"
+                        .formatted(System.currentTimeMillis())));
+
+        assertThat(classify(withHugeEnv).length(), lessThan(100));
+        assertThat(classify(withHugeEnv), not(containsString("BUILD_USER_GROUPS")));
+    }
+
+    @Test
+    public void defenseInDepthTruncationAndBounds() {
+        // Truncation: MAX_COMMAND_LENGTH = 256
+        String veryLongCommand = "UserRequest:%s@1a2b3c4d".formatted("VeryLongClassName".repeat(20));
+        String truncated = classify(veryLongCommand);
+        assertThat(truncated.length(), lessThanOrEqualTo(259));
+        assertThat(truncated, endsWith("..."));
+
+        // Pattern bound: over 1MB gracefully degrades
+        String overLimit = "Cmd[%s]@abc".formatted("x".repeat(1048577));
+        assertThat(classify(overLimit).length(), lessThanOrEqualTo(259));
+        assertThat(classify(overLimit), startsWith("Cmd["));
+
+        // ReDoS safety
+        assertEquals("Test", classify("Test%s]@abc".formatted("[".repeat(1000))));
+        assertEquals("Test", classify("Test%s@abc".formatted("[]".repeat(500))));
+        assertThat(classify("Test%s@abc".formatted("[".repeat(1000))).length(), lessThanOrEqualTo(259));
+    }
+}