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// Copyright 2024 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
package fuzzer
import (
"bytes"
"context"
"fmt"
"hash/crc32"
"math/rand"
"regexp"
"runtime"
"strings"
"sync"
"sync/atomic"
"testing"
"time"
"github.com/google/syzkaller/pkg/corpus"
"github.com/google/syzkaller/pkg/csource"
"github.com/google/syzkaller/pkg/flatrpc"
"github.com/google/syzkaller/pkg/fuzzer/queue"
"github.com/google/syzkaller/pkg/rpcserver"
"github.com/google/syzkaller/pkg/testutil"
"github.com/google/syzkaller/pkg/vminfo"
"github.com/google/syzkaller/prog"
"github.com/google/syzkaller/sys/targets"
"github.com/stretchr/testify/assert"
)
func TestFuzz(t *testing.T) {
defer checkGoroutineLeaks()
target, err := prog.GetTarget(targets.TestOS, targets.TestArch64Fuzz)
if err != nil {
t.Fatal(err)
}
sysTarget := targets.Get(target.OS, target.Arch)
if sysTarget.BrokenCompiler != "" {
t.Skipf("skipping, broken cross-compiler: %v", sysTarget.BrokenCompiler)
}
executor := csource.BuildExecutor(t, target, "../..", "-fsanitize-coverage=trace-pc", "-g")
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
corpusUpdates := make(chan corpus.NewItemEvent)
fuzzer := NewFuzzer(ctx, &Config{
Debug: true,
Corpus: corpus.NewMonitoredCorpus(ctx, corpusUpdates),
Logf: func(level int, msg string, args ...interface{}) {
if level > 1 {
return
}
t.Logf(msg, args...)
},
Coverage: true,
EnabledCalls: map[*prog.Syscall]bool{
target.SyscallMap["syz_test_fuzzer1"]: true,
},
}, rand.New(testutil.RandSource(t)), target)
go func() {
for {
select {
case <-ctx.Done():
return
case u := <-corpusUpdates:
t.Logf("new prog:\n%s", u.ProgData)
}
}
}()
tf := &testFuzzer{
t: t,
target: target,
fuzzer: fuzzer,
executor: executor,
iterLimit: 10000,
expectedCrashes: map[string]bool{
"first bug": true,
"second bug": true,
},
}
tf.run()
t.Logf("resulting corpus:")
for _, p := range fuzzer.Config.Corpus.Programs() {
t.Logf("-----")
t.Logf("%s", p.Serialize())
}
}
func BenchmarkFuzzer(b *testing.B) {
b.ReportAllocs()
target, err := prog.GetTarget(targets.TestOS, targets.TestArch64Fuzz)
if err != nil {
b.Fatal(err)
}
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
calls := map[*prog.Syscall]bool{}
for _, c := range target.Syscalls {
calls[c] = true
}
fuzzer := NewFuzzer(ctx, &Config{
Corpus: corpus.NewCorpus(ctx),
Coverage: true,
EnabledCalls: calls,
}, rand.New(rand.NewSource(time.Now().UnixNano())), target)
b.ResetTimer()
b.RunParallel(func(pb *testing.PB) {
for pb.Next() {
req := fuzzer.Next()
res, _, _ := emulateExec(req)
req.Done(res)
}
})
}
// Based on the example from Go documentation.
var crc32q = crc32.MakeTable(0xD5828281)
func emulateExec(req *queue.Request) (*queue.Result, string, error) {
serializedLines := bytes.Split(req.Prog.Serialize(), []byte("\n"))
var info flatrpc.ProgInfo
for i, call := range req.Prog.Calls {
cover := []uint64{uint64(call.Meta.ID*1024) +
uint64(crc32.Checksum(serializedLines[i], crc32q)%4)}
callInfo := &flatrpc.CallInfo{}
if req.ExecOpts.ExecFlags&flatrpc.ExecFlagCollectCover > 0 {
callInfo.Cover = cover
}
if req.ExecOpts.ExecFlags&flatrpc.ExecFlagCollectSignal > 0 {
callInfo.Signal = cover
}
info.Calls = append(info.Calls, callInfo)
}
return &queue.Result{Info: &info}, "", nil
}
type testFuzzer struct {
t testing.TB
target *prog.Target
fuzzer *Fuzzer
executor string
mu sync.Mutex
crashes map[string]int
expectedCrashes map[string]bool
iter int
iterLimit int
done func()
finished atomic.Bool
}
func (f *testFuzzer) run() {
f.crashes = make(map[string]int)
ctx, done := context.WithCancel(context.Background())
f.done = done
var output bytes.Buffer
cfg := &rpcserver.LocalConfig{
Config: rpcserver.Config{
Config: vminfo.Config{
Debug: true,
Cover: true,
Target: f.target,
Features: flatrpc.FeatureSandboxNone | flatrpc.FeatureCoverage,
Sandbox: flatrpc.ExecEnvSandboxNone,
},
Procs: 4,
Slowdown: 1,
},
Executor: f.executor,
Dir: f.t.TempDir(),
OutputWriter: &output,
}
cfg.MachineChecked = func(features flatrpc.Feature, syscalls map[*prog.Syscall]bool) queue.Source {
return f
}
if err := rpcserver.RunLocal(ctx, cfg); err != nil {
f.t.Logf("executor output:\n%s", output.String())
f.t.Fatal(err)
}
assert.Equal(f.t, len(f.expectedCrashes), len(f.crashes), "not all expected crashes were found")
assert.NotEmpty(f.t, f.fuzzer.Config.Corpus.StatProgs.Val(), "must have non-empty corpus")
assert.NotEmpty(f.t, f.fuzzer.Config.Corpus.StatSignal.Val(), "must have non-empty signal")
}
func (f *testFuzzer) Next() *queue.Request {
if f.finished.Load() {
return nil
}
req := f.fuzzer.Next()
req.ExecOpts.EnvFlags |= flatrpc.ExecEnvSignal | flatrpc.ExecEnvSandboxNone
req.ReturnOutput = true
req.ReturnError = true
req.OnDone(f.OnDone)
return req
}
func (f *testFuzzer) OnDone(req *queue.Request, res *queue.Result) bool {
// TODO: support hints emulation.
match := crashRe.FindSubmatch(res.Output)
f.mu.Lock()
defer f.mu.Unlock()
if f.finished.Load() {
// Don't touch f.crashes in this case b/c it can cause races with the main goroutine,
// and logging can cause "Log in goroutine after TestFuzz has completed" panic.
return true
}
if match != nil {
crash := string(match[1])
f.t.Logf("CRASH: %s", crash)
res.Status = queue.Crashed
if !f.expectedCrashes[crash] {
f.t.Errorf("unexpected crash: %q", crash)
}
f.crashes[crash]++
}
f.iter++
corpusProgs := f.fuzzer.Config.Corpus.StatProgs.Val()
signal := f.fuzzer.Config.Corpus.StatSignal.Val()
if f.iter%100 == 0 {
f.t.Logf("<iter %d>: corpus %d, signal %d, max signal %d, crash types %d, running jobs %d",
f.iter, corpusProgs, signal, len(f.fuzzer.Cover.maxSignal),
len(f.crashes), f.fuzzer.statJobs.Val())
}
criteriaMet := len(f.crashes) == len(f.expectedCrashes) &&
corpusProgs > 0 && signal > 0
if f.iter > f.iterLimit || criteriaMet {
f.done()
f.finished.Store(true)
}
return true
}
var crashRe = regexp.MustCompile(`{{CRASH: (.*?)}}`)
func checkGoroutineLeaks() {
// Inspired by src/net/http/main_test.go.
buf := make([]byte, 2<<20)
err := ""
for i := 0; i < 3; i++ {
buf = buf[:runtime.Stack(buf, true)]
err = ""
for _, g := range strings.Split(string(buf), "\n\n") {
if !strings.Contains(g, "pkg/fuzzer/fuzzer.go") {
continue
}
err = fmt.Sprintf("%sLeaked goroutine:\n%s", err, g)
}
if err == "" {
return
}
// Give ctx.Done() a chance to propagate to all goroutines.
time.Sleep(100 * time.Millisecond)
}
if err != "" {
panic(err)
}
}
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