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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 main
import (
"bytes"
"context"
"errors"
"fmt"
"time"
flatbuffers "github.com/google/flatbuffers/go"
"github.com/google/syzkaller/pkg/flatrpc"
"github.com/google/syzkaller/pkg/fuzzer/queue"
"github.com/google/syzkaller/pkg/log"
"github.com/google/syzkaller/pkg/manager"
"github.com/google/syzkaller/vm"
"github.com/google/syzkaller/vm/dispatcher"
)
func (mgr *Manager) snapshotInstance(ctx context.Context, inst *vm.Instance, updInfo dispatcher.UpdateInfo) {
queue.StatNumFuzzing.Add(1)
defer queue.StatNumFuzzing.Add(-1)
updInfo(func(info *dispatcher.Info) {
info.Status = "snapshot fuzzing"
})
err := mgr.snapshotLoop(ctx, inst)
if err != nil {
log.Error(err)
}
}
func (mgr *Manager) snapshotLoop(ctx context.Context, inst *vm.Instance) error {
executor, err := inst.Copy(mgr.cfg.ExecutorBin)
if err != nil {
return err
}
// All network connections (including ssh) will break once we start restoring snapshots.
// So we start a background process and log to /dev/kmsg.
cmd := fmt.Sprintf("nohup %v exec snapshot 1>/dev/null 2>/dev/kmsg </dev/null &", executor)
if _, _, err := inst.Run(time.Hour, mgr.reporter, cmd); err != nil {
return err
}
builder := flatbuffers.NewBuilder(0)
var envFlags flatrpc.ExecEnv
for first := true; ctx.Err() == nil; first = false {
queue.StatExecs.Add(1)
req := mgr.snapshotSource.Next(inst.Index())
if first {
envFlags = req.ExecOpts.EnvFlags
if err := mgr.snapshotSetup(inst, builder, envFlags); err != nil {
req.Done(&queue.Result{Status: queue.Crashed})
return err
}
}
if envFlags != req.ExecOpts.EnvFlags {
panic(fmt.Sprintf("request env flags has changed: 0x%x -> 0x%x",
envFlags, req.ExecOpts.EnvFlags))
}
res, output, err := mgr.snapshotRun(inst, builder, req)
if err != nil {
req.Done(&queue.Result{Status: queue.Crashed})
return err
}
if mgr.reporter.ContainsCrash(output) {
res.Status = queue.Crashed
rep := mgr.reporter.Parse(output)
buf := new(bytes.Buffer)
fmt.Fprintf(buf, "program:\n%s\n", req.Prog.Serialize())
buf.Write(rep.Output)
rep.Output = buf.Bytes()
mgr.crashes <- &manager.Crash{Report: rep}
}
req.Done(res)
}
return nil
}
func (mgr *Manager) snapshotSetup(inst *vm.Instance, builder *flatbuffers.Builder, env flatrpc.ExecEnv) error {
msg := flatrpc.SnapshotHandshakeT{
CoverEdges: mgr.cfg.Experimental.CoverEdges,
Kernel64Bit: mgr.cfg.SysTarget.PtrSize == 8,
Slowdown: int32(mgr.cfg.Timeouts.Slowdown),
SyscallTimeoutMs: int32(mgr.cfg.Timeouts.Syscall / time.Millisecond),
ProgramTimeoutMs: int32(mgr.cfg.Timeouts.Program / time.Millisecond),
Features: mgr.enabledFeatures,
EnvFlags: env,
SandboxArg: mgr.cfg.SandboxArg,
}
builder.Reset()
builder.Finish(msg.Pack(builder))
return inst.SetupSnapshot(builder.FinishedBytes())
}
func (mgr *Manager) snapshotRun(inst *vm.Instance, builder *flatbuffers.Builder, req *queue.Request) (
*queue.Result, []byte, error) {
progData, err := req.Prog.SerializeForExec()
if err != nil {
queue.StatExecBufferTooSmall.Add(1)
return &queue.Result{Status: queue.ExecFailure}, nil, nil
}
msg := flatrpc.SnapshotRequestT{
ExecFlags: req.ExecOpts.ExecFlags,
NumCalls: int32(len(req.Prog.Calls)),
ProgData: progData,
}
for _, call := range req.ReturnAllSignal {
if call < 0 {
msg.AllExtraSignal = true
} else {
msg.AllCallSignal |= 1 << call
}
}
builder.Reset()
builder.Finish(msg.Pack(builder))
start := time.Now()
resData, output, err := inst.RunSnapshot(builder.FinishedBytes())
if err != nil {
return nil, nil, err
}
elapsed := time.Since(start)
res := parseExecResult(resData)
if res.Info != nil {
res.Info.Elapsed = uint64(elapsed)
for len(res.Info.Calls) < len(req.Prog.Calls) {
res.Info.Calls = append(res.Info.Calls, &flatrpc.CallInfo{
Error: 999,
})
}
res.Info.Calls = res.Info.Calls[:len(req.Prog.Calls)]
if len(res.Info.ExtraRaw) != 0 {
res.Info.Extra = res.Info.ExtraRaw[0]
for _, info := range res.Info.ExtraRaw[1:] {
res.Info.Extra.Cover = append(res.Info.Extra.Cover, info.Cover...)
res.Info.Extra.Signal = append(res.Info.Extra.Signal, info.Signal...)
}
res.Info.ExtraRaw = nil
}
}
ret := &queue.Result{
Status: queue.Success,
Info: res.Info,
}
if res.Error != "" {
ret.Status = queue.ExecFailure
ret.Err = errors.New(res.Error)
}
if req.ReturnOutput {
ret.Output = output
}
return ret, output, nil
}
func parseExecResult(data []byte) *flatrpc.ExecResult {
if len(data) < flatbuffers.SizeUint32 {
return &flatrpc.ExecResult{
Error: "the buffer is too small",
}
}
raw, err := flatrpc.Parse[*flatrpc.ExecutorMessageRaw](data[flatbuffers.SizeUint32:])
if err != nil {
// Don't consider result parsing error as an infrastructure error,
// it's just the test program corrupted memory.
return &flatrpc.ExecResult{
Error: err.Error(),
}
}
res, ok := raw.Msg.Value.(*flatrpc.ExecResult)
if !ok {
return &flatrpc.ExecResult{
Error: "result is not ExecResult",
}
}
return res
}
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