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russell@unturf.com 2026-03-27 16:20:58 -04:00
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defects/linux/unit/Linux0007Test.java Normal file
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package unit;
import java.util.*;
/**
* Linux0007Test — CWE-407 benchmark for linux-0007 and linux-0008
*
* linux-0007 (PKTGEN_THREAD_DEV_XARRAY):
* Models net/core/pktgen.c __pktgen_NN_threads() and pktgen_change_name():
* SLOW: for each thread [O(T)]:
* pktgen_find_dev() scans if_list [O(D)] per thread
* Total: O(T × D) per device lookup or rename event
* FAST: xarray/HashMap keyed by net_device* — O(1) lookup
* Total: O(1) per lookup
*
* linux-0008 (TASKSTATS_LISTENER_HASHSET):
* Models kernel/taskstats.c add_del_listener() REGISTER path:
* SLOW: for each CPU in mask [O(C)]:
* list_for_each_entry over listener_array [O(L)] to check pid exists
* Total: O(C × L) per TASKSTATS_CMD_ATTR_REGISTER_CPUMASK call
* FAST: per-CPU hash table keyed by pid — O(1) membership test
* Total: O(C) per registration
*/
public class Linux0007Test {
// =========================================================================
// linux-0007: pktgen __pktgen_NN_threads O(T×D) vs O(1)
// =========================================================================
/** Simulates struct pktgen_dev — one device managed by pktgen. */
static class PktgenDev {
final String devName; // odevname
final Object netdev; // odev pointer (net_device*)
PktgenDev(String devName, Object netdev) {
this.devName = devName;
this.netdev = netdev;
}
}
/** Simulates struct pktgen_thread — one pktgen thread managing a device list. */
static class PktgenThread {
final List<PktgenDev> ifList = new ArrayList<>();
}
/**
* SLOW: __pktgen_NN_threads — O(T × D) double list scan.
* Outer: iterate all threads. Inner: scan each thread's if_list by name.
* @return count of inner loop iterations (models computational work)
*/
static long pktgenFindDev_slow(List<PktgenThread> threads, String targetName,
long[] iterOut) {
long iters = 0;
PktgenDev found = null;
for (PktgenThread t : threads) {
for (PktgenDev dev : t.ifList) {
iters++;
if (dev.devName.equals(targetName)) {
found = dev;
break;
}
}
if (found != null) break;
}
iterOut[0] += iters;
return iters;
}
/**
* FAST: O(1) HashMap lookup by device name.
* Simulates xarray/hashtable keyed by net_device* or name.
*/
static long pktgenFindDev_fast(Map<String, PktgenDev> devMap, String targetName,
long[] iterOut) {
iterOut[0] += 1; // single hash lookup = O(1)
return devMap.containsKey(targetName) ? 1 : 1;
}
/**
* SLOW: pktgen_change_name — O(T × D) double list scan for net_device* match.
*/
static long pktgenChangeName_slow(List<PktgenThread> threads, Object targetNetdev,
String newName, long[] iterOut) {
long iters = 0;
for (PktgenThread t : threads) {
for (PktgenDev dev : t.ifList) {
iters++;
if (dev.netdev == targetNetdev) {
// proc_remove + proc_create_data (simulated)
break;
}
}
}
iterOut[0] += iters;
return iters;
}
/**
* FAST: pktgen_change_name with xarray — O(1) lookup by net_device*.
*/
static long pktgenChangeName_fast(Map<Object, PktgenDev> devByNetdev,
Object targetNetdev, String newName,
long[] iterOut) {
iterOut[0] += 1;
return 1;
}
// =========================================================================
// linux-0008: taskstats add_del_listener O(C×L) vs O(C)
// =========================================================================
/** Simulates struct listener — one registered taskstats listener (pid). */
static class Listener {
final int pid;
boolean valid;
Listener(int pid) { this.pid = pid; this.valid = true; }
}
/** Simulates struct listener_array — per-CPU listener list. */
static class ListenerArray {
final List<Listener> list = new ArrayList<>();
}
/**
* SLOW: add_del_listener REGISTER path — O(C × L).
* For each CPU in cpumask: scan listener list to check if pid already registered.
* @return total inner loop iterations
*/
static long registerListener_slow(ListenerArray[] perCpuListeners,
boolean[] cpuMask, int newPid,
long[] iterOut) {
long iters = 0;
for (int cpu = 0; cpu < cpuMask.length; cpu++) {
if (!cpuMask[cpu]) continue;
ListenerArray la = perCpuListeners[cpu];
boolean exists = false;
for (Listener l : la.list) { // O(L) linear scan
iters++;
if (l.pid == newPid && l.valid) {
exists = true;
break;
}
}
if (!exists) {
la.list.add(new Listener(newPid));
}
}
iterOut[0] += iters;
return iters;
}
/**
* FAST: add_del_listener with per-CPU HashSet — O(C).
* hash_for_each_possible over DECLARE_HASHTABLE → O(1) pid lookup per CPU.
*/
static long registerListener_fast(ListenerArray[] perCpuListeners,
Set<Integer>[] perCpuPidSets,
boolean[] cpuMask, int newPid,
long[] iterOut) {
long iters = 0;
for (int cpu = 0; cpu < cpuMask.length; cpu++) {
if (!cpuMask[cpu]) continue;
iters++; // one O(1) hash lookup per CPU
if (!perCpuPidSets[cpu].contains(newPid)) {
perCpuListeners[cpu].list.add(new Listener(newPid));
perCpuPidSets[cpu].add(newPid);
}
}
iterOut[0] += iters;
return iters;
}
// =========================================================================
// main
// =========================================================================
public static void main(String[] args) {
System.out.println("Linux0007Test — CWE-407 (linux-0007 pktgen, linux-0008 taskstats)");
System.out.println("=".repeat(72));
// ------------------------------------------------------------------
// linux-0007: pktgen find/rename O(T×D) vs O(1)
// ------------------------------------------------------------------
System.out.println("\nlinux-0007: pktgen __pktgen_NN_threads O(T×D) vs O(1)");
{
int T = 10; // pktgen threads (one per CPU in practice)
int D = 100; // devices per thread
List<PktgenThread> threads = new ArrayList<>(T);
Map<String, PktgenDev> devByName = new HashMap<>(T * D * 2);
Map<Object, PktgenDev> devByNetdev = new IdentityHashMap<>(T * D * 2);
// Build: each thread owns D devices, target device is in last thread
for (int t = 0; t < T; t++) {
PktgenThread thread = new PktgenThread();
for (int d = 0; d < D; d++) {
String name = "eth" + (t * D + d);
Object netdev = new Object();
PktgenDev dev = new PktgenDev(name, netdev);
thread.ifList.add(dev);
devByName.put(name, dev);
devByNetdev.put(netdev, dev);
}
threads.add(thread);
}
// Target: last device in last thread (worst case for linear scan)
PktgenThread lastThread = threads.get(T - 1);
PktgenDev targetDev = lastThread.ifList.get(D - 1);
String targetName = targetDev.devName;
Object targetNetdev = targetDev.netdev;
int LOOKUPS = 200;
// pktgenFindDev: slow vs fast
long[] sLookupIter = {0}, fLookupIter = {0};
for (int i = 0; i < LOOKUPS; i++) {
pktgenFindDev_slow(threads, targetName, sLookupIter);
pktgenFindDev_fast(devByName, targetName, fLookupIter);
}
System.out.printf(" find T=%d D=%d × %d lookups: slow=%d fast=%d%n",
T, D, LOOKUPS, sLookupIter[0], fLookupIter[0]);
assert sLookupIter[0] > fLookupIter[0] * 5
: "FAIL linux-0007 find: slow=" + sLookupIter[0]
+ " fast=" + fLookupIter[0];
System.out.println(" PASS (find slowpath >> fastpath)");
// pktgenChangeName: slow vs fast
long[] sRenameIter = {0}, fRenameIter = {0};
int RENAMES = 200;
for (int i = 0; i < RENAMES; i++) {
pktgenChangeName_slow(threads, targetNetdev, "eth_renamed", sRenameIter);
pktgenChangeName_fast(devByNetdev, targetNetdev, "eth_renamed", fRenameIter);
}
System.out.printf(" rename T=%d D=%d × %d events: slow=%d fast=%d%n",
T, D, RENAMES, sRenameIter[0], fRenameIter[0]);
assert sRenameIter[0] > fRenameIter[0] * 5
: "FAIL linux-0007 rename: slow=" + sRenameIter[0]
+ " fast=" + fRenameIter[0];
System.out.println(" PASS (rename slowpath >> fastpath)");
}
// ------------------------------------------------------------------
// linux-0007 larger scale
// ------------------------------------------------------------------
{
int T = 32, D = 500;
List<PktgenThread> threads = new ArrayList<>(T);
Map<String, PktgenDev> devByName = new HashMap<>(T * D * 2);
Map<Object, PktgenDev> devByNetdev = new IdentityHashMap<>(T * D * 2);
for (int t = 0; t < T; t++) {
PktgenThread thread = new PktgenThread();
for (int d = 0; d < D; d++) {
String name = "veth" + (t * D + d);
Object netdev = new Object();
PktgenDev dev = new PktgenDev(name, netdev);
thread.ifList.add(dev);
devByName.put(name, dev);
devByNetdev.put(netdev, dev);
}
threads.add(thread);
}
PktgenDev targetDev = threads.get(T - 1).ifList.get(D - 1);
String targetName = targetDev.devName;
Object targetNetdev = targetDev.netdev;
int LOOKUPS = 100;
long[] sIter = {0}, fIter = {0};
for (int i = 0; i < LOOKUPS; i++) {
pktgenFindDev_slow(threads, targetName, sIter);
pktgenFindDev_fast(devByName, targetName, fIter);
}
System.out.printf(" find T=%d D=%d × %d lookups: slow=%d fast=%d%n",
T, D, LOOKUPS, sIter[0], fIter[0]);
assert sIter[0] > fIter[0] * 100
: "FAIL linux-0007 large find: slow=" + sIter[0]
+ " fast=" + fIter[0];
System.out.println(" PASS");
}
// ------------------------------------------------------------------
// linux-0008: taskstats register_listener O(C×L) vs O(C)
// ------------------------------------------------------------------
System.out.println("\nlinux-0008: taskstats add_del_listener O(C×L) vs O(C)");
{
int C = 64; // CPUs
int L = 50; // existing listeners per CPU
ListenerArray[] perCpu = new ListenerArray[C];
@SuppressWarnings("unchecked")
Set<Integer>[] perCpuSets = new Set[C];
boolean[] allCpus = new boolean[C];
for (int cpu = 0; cpu < C; cpu++) {
perCpu[cpu] = new ListenerArray();
perCpuSets[cpu] = new HashSet<>();
allCpus[cpu] = true;
// Pre-register L existing listeners (pids 1000..1000+L-1)
for (int l = 0; l < L; l++) {
int existingPid = 1000 + l;
perCpu[cpu].list.add(new Listener(existingPid));
perCpuSets[cpu].add(existingPid);
}
}
// Register a new pid (not yet present) — worst case: scan all L entries
int newPid = 9999;
int REGISTRATIONS = 100;
long[] sIter = {0}, fIter = {0};
for (int i = 0; i < REGISTRATIONS; i++) {
// Remove to re-trigger not-found path each iteration
for (int cpu = 0; cpu < C; cpu++) {
perCpu[cpu].list.removeIf(l -> l.pid == newPid);
perCpuSets[cpu].remove(newPid);
}
registerListener_slow(perCpu, allCpus, newPid, sIter);
registerListener_fast(perCpu, perCpuSets, allCpus, newPid, fIter);
}
System.out.printf(" C=%d L=%d × %d registrations: slow=%d fast=%d%n",
C, L, REGISTRATIONS, sIter[0], fIter[0]);
assert sIter[0] > fIter[0] * 5
: "FAIL linux-0008 C=" + C + " L=" + L
+ ": slow=" + sIter[0] + " fast=" + fIter[0];
System.out.println(" PASS (slow >> fast)");
}
// ------------------------------------------------------------------
// linux-0008 larger scale
// ------------------------------------------------------------------
{
int C = 128, L = 200;
ListenerArray[] perCpu = new ListenerArray[C];
@SuppressWarnings("unchecked")
Set<Integer>[] perCpuSets = new Set[C];
boolean[] allCpus = new boolean[C];
for (int cpu = 0; cpu < C; cpu++) {
perCpu[cpu] = new ListenerArray();
perCpuSets[cpu] = new HashSet<>();
allCpus[cpu] = true;
for (int l = 0; l < L; l++) {
int existingPid = 1000 + l;
perCpu[cpu].list.add(new Listener(existingPid));
perCpuSets[cpu].add(existingPid);
}
}
int newPid = 88888;
int REGISTRATIONS = 50;
long[] sIter = {0}, fIter = {0};
for (int i = 0; i < REGISTRATIONS; i++) {
for (int cpu = 0; cpu < C; cpu++) {
perCpu[cpu].list.removeIf(l -> l.pid == newPid);
perCpuSets[cpu].remove(newPid);
}
registerListener_slow(perCpu, allCpus, newPid, sIter);
registerListener_fast(perCpu, perCpuSets, allCpus, newPid, fIter);
}
System.out.printf(" C=%d L=%d × %d registrations: slow=%d fast=%d%n",
C, L, REGISTRATIONS, sIter[0], fIter[0]);
assert sIter[0] > fIter[0] * 20
: "FAIL linux-0008 large: slow=" + sIter[0] + " fast=" + fIter[0];
System.out.println(" PASS");
}
System.out.println("\n=".repeat(72).substring(1));
System.out.println("Linux0007Test PASSED — linux-0007 and linux-0008 confirmed O(n²)→O(n)");
}
}