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// Copyright 2018 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.
// syz-bisect runs bisection to find cause/fix commit for a crash.
//
// The tool is originally created to test pkg/bisect logic.
//
// The tool requires a config file passed in -config flag, see Config type below for details,
// and a directory with info about the crash passed in -crash flag).
// If -fix flag is specified, it does fix bisection. Otherwise it does cause bisection. Also
// wanted syzkaller and kernel commits can be specified using -syzkaller_commit and
// -kernel_commit. HEAD is used if commits are not specified.
//
// The crash dir should contain the following files:
// - repro.cprog or repro.prog: reproducer for the crash
// - repro.opts: syzkaller reproducer options (e.g. {"procs":1,"sandbox":"none",...}) (optional)
//
// The tool stores bisection result into cause.commit or fix.commit.
package main
import (
"encoding/json"
"flag"
"fmt"
"os"
"path/filepath"
"github.com/google/syzkaller/pkg/bisect"
"github.com/google/syzkaller/pkg/config"
"github.com/google/syzkaller/pkg/debugtracer"
"github.com/google/syzkaller/pkg/mgrconfig"
"github.com/google/syzkaller/pkg/osutil"
"github.com/google/syzkaller/pkg/vcs"
)
var (
flagConfig = flag.String("config", "", "bisect config file")
flagCrash = flag.String("crash", "", "dir with crash info")
flagFix = flag.Bool("fix", false, "search for crash fix")
flagKernelCommit = flag.String("kernel_commit", "", "original kernel commit")
flagKernelCommitTitle = flag.String("kernel_commit_title", "", "original kernel commit title")
flagSyzkallerCommit = flag.String("syzkaller_commit", "", "original syzkaller commit")
)
type Config struct {
Compiler string `json:"compiler"`
// Currently either 'gcc' or 'clang'. Note that pkg/bisect requires
// explicit plumbing for every os/compiler combination.
CompilerType string `json:"compiler_type"`
Make string `json:"make"`
// BinDir must point to a dir that contains compilers required to build
// older versions of the kernel. For linux, it needs to include several
// compiler versions.
BinDir string `json:"bin_dir"`
Linker string `json:"linker"`
Ccache string `json:"ccache"`
KernelRepo string `json:"kernel_repo"`
KernelBranch string `json:"kernel_branch"`
SyzkallerRepo string `json:"syzkaller_repo"`
// Directory with user-space system for building kernel images
// (for linux that's the input to tools/create-gce-image.sh).
Userspace string `json:"userspace"`
// Sysctl/cmdline files used to build the image which was used to crash the kernel, e.g. see:
// dashboard/config/upstream.sysctl
// dashboard/config/upstream-selinux.cmdline
Sysctl string `json:"sysctl"`
Cmdline string `json:"cmdline"`
CrossTree bool `json:"cross_tree"`
Backports []vcs.BackportCommit `json:"backports"`
KernelConfig string `json:"kernel_config"`
KernelBaselineConfig string `json:"kernel_baseline_config"`
// Manager config that was used to obtain the crash.
Manager json.RawMessage `json:"manager"`
}
func main() {
flag.Parse()
os.Setenv("SYZ_DISABLE_SANDBOXING", "yes")
mycfg := new(Config)
if err := config.LoadFile(*flagConfig, mycfg); err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
mgrcfg, err := mgrconfig.LoadData(mycfg.Manager)
if err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
if mgrcfg.Workdir == "" {
mgrcfg.Workdir, err = os.MkdirTemp("", "syz-bisect")
if err != nil {
fmt.Fprintf(os.Stderr, "failed to create temp dir: %v\n", err)
os.Exit(1)
}
defer os.RemoveAll(mgrcfg.Workdir)
}
cfg := &bisect.Config{
Trace: &debugtracer.GenericTracer{
TraceWriter: os.Stdout,
OutDir: *flagCrash,
},
Fix: *flagFix,
DefaultCompiler: mycfg.Compiler,
CompilerType: mycfg.CompilerType,
Make: mycfg.Make,
Linker: mycfg.Linker,
BinDir: mycfg.BinDir,
Ccache: mycfg.Ccache,
CrossTree: mycfg.CrossTree,
Kernel: bisect.KernelConfig{
Repo: mycfg.KernelRepo,
Branch: mycfg.KernelBranch,
Commit: *flagKernelCommit,
CommitTitle: *flagKernelCommitTitle,
Userspace: mycfg.Userspace,
Sysctl: mycfg.Sysctl,
Cmdline: mycfg.Cmdline,
Backports: mycfg.Backports,
},
Syzkaller: bisect.SyzkallerConfig{
Repo: mycfg.SyzkallerRepo,
Commit: *flagSyzkallerCommit,
},
Manager: mgrcfg,
}
loadFile("", mycfg.KernelConfig, &cfg.Kernel.Config, true)
loadFile("", mycfg.KernelBaselineConfig, &cfg.Kernel.BaselineConfig, false)
loadFile(*flagCrash, "repro.prog", &cfg.Repro.Syz, false)
loadFile(*flagCrash, "repro.cprog", &cfg.Repro.C, false)
loadFile(*flagCrash, "repro.opts", &cfg.Repro.Opts, false)
if len(cfg.Repro.Syz) == 0 && len(cfg.Repro.C) == 0 {
fmt.Fprintf(os.Stderr, "no repro.cprog or repro.prog found\n")
os.Exit(1)
}
if cfg.Syzkaller.Commit == "" {
cfg.Syzkaller.Commit = vcs.HEAD
}
if cfg.Kernel.Commit == "" {
cfg.Kernel.Commit = vcs.HEAD
}
result, err := bisect.Run(cfg)
if err != nil {
fmt.Fprintf(os.Stderr, "bisection failed: %v\n", err)
os.Exit(1)
}
saveResultCommits(result.Commits)
}
func loadFile(path, file string, dst *[]byte, mandatory bool) {
filename := filepath.Join(path, file)
if !mandatory && !osutil.IsExist(filename) {
return
}
data, err := os.ReadFile(filename)
if err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
*dst = data
}
func saveResultCommits(commits []*vcs.Commit) {
var result string
if len(commits) > 0 {
for _, commit := range commits {
result = result + commit.Hash + "\n"
}
} else if *flagFix {
result = "the crash still happens on HEAD\n"
} else {
result = "the crash already happened on the oldest tested release\n"
}
var fileName string
if *flagFix {
fileName = filepath.Join(*flagCrash, "fix.commit")
} else {
fileName = filepath.Join(*flagCrash, "cause.commit")
}
osutil.WriteFile(fileName, []byte(result))
}
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