// https://syzkaller.appspot.com/bug?id=47d69b834738f86cd774713f4c96fd5be7ad9202
// autogenerated by syzkaller (http://github.com/google/syzkaller)

#define _GNU_SOURCE
#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <errno.h>
#include <errno.h>
#include <errno.h>
#include <fcntl.h>
#include <fcntl.h>
#include <fcntl.h>
#include <linux/futex.h>
#include <linux/net.h>
#include <netinet/in.h>
#include <pthread.h>
#include <sched.h>
#include <signal.h>
#include <signal.h>
#include <stdarg.h>
#include <stdarg.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdio.h>
#include <stdio.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mount.h>
#include <sys/mount.h>
#include <sys/prctl.h>
#include <sys/prctl.h>
#include <sys/resource.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/stat.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/sysmacros.h>
#include <sys/time.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

__attribute__((noreturn)) static void doexit(int status)
{
  volatile unsigned i;
  syscall(__NR_exit_group, status);
  for (i = 0;; i++) {
  }
}
#include <errno.h>
#include <stdarg.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>

const int kFailStatus = 67;
const int kRetryStatus = 69;

static void fail(const char* msg, ...)
{
  int e = errno;
  va_list args;
  va_start(args, msg);
  vfprintf(stderr, msg, args);
  va_end(args);
  fprintf(stderr, " (errno %d)\n", e);
  doexit((e == ENOMEM || e == EAGAIN) ? kRetryStatus : kFailStatus);
}

static void exitf(const char* msg, ...)
{
  int e = errno;
  va_list args;
  va_start(args, msg);
  vfprintf(stderr, msg, args);
  va_end(args);
  fprintf(stderr, " (errno %d)\n", e);
  doexit(kRetryStatus);
}

static uint64_t current_time_ms()
{
  struct timespec ts;

  if (clock_gettime(CLOCK_MONOTONIC, &ts))
    fail("clock_gettime failed");
  return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}

static void use_temporary_dir()
{
  char tmpdir_template[] = "./syzkaller.XXXXXX";
  char* tmpdir = mkdtemp(tmpdir_template);
  if (!tmpdir)
    fail("failed to mkdtemp");
  if (chmod(tmpdir, 0777))
    fail("failed to chmod");
  if (chdir(tmpdir))
    fail("failed to chdir");
}

static uintptr_t syz_fuse_mount(uintptr_t a0, uintptr_t a1, uintptr_t a2,
                                uintptr_t a3, uintptr_t a4, uintptr_t a5)
{
  uint64_t target = a0;
  uint64_t mode = a1;
  uint64_t uid = a2;
  uint64_t gid = a3;
  uint64_t maxread = a4;
  uint64_t flags = a5;

  int fd = open("/dev/fuse", O_RDWR);
  if (fd == -1)
    return fd;
  char buf[1024];
  sprintf(buf, "fd=%d,user_id=%ld,group_id=%ld,rootmode=0%o", fd, (long)uid,
          (long)gid, (unsigned)mode & ~3u);
  if (maxread != 0)
    sprintf(buf + strlen(buf), ",max_read=%ld", (long)maxread);
  if (mode & 1)
    strcat(buf, ",default_permissions");
  if (mode & 2)
    strcat(buf, ",allow_other");
  syscall(SYS_mount, "", target, "fuse", flags, buf);
  return fd;
}

static uintptr_t syz_fuseblk_mount(uintptr_t a0, uintptr_t a1, uintptr_t a2,
                                   uintptr_t a3, uintptr_t a4, uintptr_t a5,
                                   uintptr_t a6, uintptr_t a7)
{
  uint64_t target = a0;
  uint64_t blkdev = a1;
  uint64_t mode = a2;
  uint64_t uid = a3;
  uint64_t gid = a4;
  uint64_t maxread = a5;
  uint64_t blksize = a6;
  uint64_t flags = a7;

  int fd = open("/dev/fuse", O_RDWR);
  if (fd == -1)
    return fd;
  if (syscall(SYS_mknodat, AT_FDCWD, blkdev, S_IFBLK, makedev(7, 199)))
    return fd;
  char buf[256];
  sprintf(buf, "fd=%d,user_id=%ld,group_id=%ld,rootmode=0%o", fd, (long)uid,
          (long)gid, (unsigned)mode & ~3u);
  if (maxread != 0)
    sprintf(buf + strlen(buf), ",max_read=%ld", (long)maxread);
  if (blksize != 0)
    sprintf(buf + strlen(buf), ",blksize=%ld", (long)blksize);
  if (mode & 1)
    strcat(buf, ",default_permissions");
  if (mode & 2)
    strcat(buf, ",allow_other");
  syscall(SYS_mount, blkdev, target, "fuseblk", flags, buf);
  return fd;
}

static bool write_file(const char* file, const char* what, ...)
{
  char buf[1024];
  va_list args;
  va_start(args, what);
  vsnprintf(buf, sizeof(buf), what, args);
  va_end(args);
  buf[sizeof(buf) - 1] = 0;
  int len = strlen(buf);

  int fd = open(file, O_WRONLY | O_CLOEXEC);
  if (fd == -1)
    return false;
  if (write(fd, buf, len) != len) {
    int err = errno;
    close(fd);
    errno = err;
    return false;
  }
  close(fd);
  return true;
}

static void setup_cgroups()
{
  if (mkdir("/syzcgroup", 0777)) {
  }
  if (mkdir("/syzcgroup/unified", 0777)) {
  }
  if (mount("none", "/syzcgroup/unified", "cgroup2", 0, NULL)) {
  }
  if (chmod("/syzcgroup/unified", 0777)) {
  }
  if (!write_file("/syzcgroup/unified/cgroup.subtree_control",
                  "+cpu +memory +io +pids +rdma")) {
  }
  if (mkdir("/syzcgroup/cpu", 0777)) {
  }
  if (mount("none", "/syzcgroup/cpu", "cgroup", 0,
            "cpuset,cpuacct,perf_event,hugetlb")) {
  }
  if (!write_file("/syzcgroup/cpu/cgroup.clone_children", "1")) {
  }
  if (chmod("/syzcgroup/cpu", 0777)) {
  }
  if (mkdir("/syzcgroup/net", 0777)) {
  }
  if (mount("none", "/syzcgroup/net", "cgroup", 0,
            "net_cls,net_prio,devices,freezer")) {
  }
  if (chmod("/syzcgroup/net", 0777)) {
  }
}

static void setup_binfmt_misc()
{
  if (!write_file("/proc/sys/fs/binfmt_misc/register",
                  ":syz0:M:0:syz0::./file0:")) {
  }
  if (!write_file("/proc/sys/fs/binfmt_misc/register",
                  ":syz1:M:1:yz1::./file0:POC")) {
  }
}

static void loop();

static void sandbox_common()
{
  prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
  setpgrp();
  setsid();

  struct rlimit rlim;
  rlim.rlim_cur = rlim.rlim_max = 160 << 20;
  setrlimit(RLIMIT_AS, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 8 << 20;
  setrlimit(RLIMIT_MEMLOCK, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 136 << 20;
  setrlimit(RLIMIT_FSIZE, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 1 << 20;
  setrlimit(RLIMIT_STACK, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 0;
  setrlimit(RLIMIT_CORE, &rlim);

  if (unshare(CLONE_NEWNS)) {
  }
  if (unshare(CLONE_NEWIPC)) {
  }
  if (unshare(0x02000000)) {
  }
  if (unshare(CLONE_NEWUTS)) {
  }
  if (unshare(CLONE_SYSVSEM)) {
  }
}

static int do_sandbox_none(void)
{
  if (unshare(CLONE_NEWPID)) {
  }
  int pid = fork();
  if (pid < 0)
    fail("sandbox fork failed");
  if (pid)
    return pid;

  setup_cgroups();
  setup_binfmt_misc();
  sandbox_common();
  if (unshare(CLONE_NEWNET)) {
  }

  loop();
  doexit(1);
}

#define XT_TABLE_SIZE 1536
#define XT_MAX_ENTRIES 10

struct xt_counters {
  uint64_t pcnt, bcnt;
};

struct ipt_getinfo {
  char name[32];
  unsigned int valid_hooks;
  unsigned int hook_entry[5];
  unsigned int underflow[5];
  unsigned int num_entries;
  unsigned int size;
};

struct ipt_get_entries {
  char name[32];
  unsigned int size;
  void* entrytable[XT_TABLE_SIZE / sizeof(void*)];
};

struct ipt_replace {
  char name[32];
  unsigned int valid_hooks;
  unsigned int num_entries;
  unsigned int size;
  unsigned int hook_entry[5];
  unsigned int underflow[5];
  unsigned int num_counters;
  struct xt_counters* counters;
  char entrytable[XT_TABLE_SIZE];
};

struct ipt_table_desc {
  const char* name;
  struct ipt_getinfo info;
  struct ipt_replace replace;
};

static struct ipt_table_desc ipv4_tables[] = {
    {.name = "filter"}, {.name = "nat"},      {.name = "mangle"},
    {.name = "raw"},    {.name = "security"},
};

static struct ipt_table_desc ipv6_tables[] = {
    {.name = "filter"}, {.name = "nat"},      {.name = "mangle"},
    {.name = "raw"},    {.name = "security"},
};

#define IPT_BASE_CTL 64
#define IPT_SO_SET_REPLACE (IPT_BASE_CTL)
#define IPT_SO_GET_INFO (IPT_BASE_CTL)
#define IPT_SO_GET_ENTRIES (IPT_BASE_CTL + 1)

struct arpt_getinfo {
  char name[32];
  unsigned int valid_hooks;
  unsigned int hook_entry[3];
  unsigned int underflow[3];
  unsigned int num_entries;
  unsigned int size;
};

struct arpt_get_entries {
  char name[32];
  unsigned int size;
  void* entrytable[XT_TABLE_SIZE / sizeof(void*)];
};

struct arpt_replace {
  char name[32];
  unsigned int valid_hooks;
  unsigned int num_entries;
  unsigned int size;
  unsigned int hook_entry[3];
  unsigned int underflow[3];
  unsigned int num_counters;
  struct xt_counters* counters;
  char entrytable[XT_TABLE_SIZE];
};

struct arpt_table_desc {
  const char* name;
  struct arpt_getinfo info;
  struct arpt_replace replace;
};

static struct arpt_table_desc arpt_tables[] = {
    {.name = "filter"},
};

#define ARPT_BASE_CTL 96
#define ARPT_SO_SET_REPLACE (ARPT_BASE_CTL)
#define ARPT_SO_GET_INFO (ARPT_BASE_CTL)
#define ARPT_SO_GET_ENTRIES (ARPT_BASE_CTL + 1)

static void checkpoint_iptables(struct ipt_table_desc* tables, int num_tables,
                                int family, int level)
{
  struct ipt_get_entries entries;
  socklen_t optlen;
  int fd, i;

  fd = socket(family, SOCK_STREAM, IPPROTO_TCP);
  if (fd == -1) {
    switch (errno) {
    case EAFNOSUPPORT:
    case ENOPROTOOPT:
      return;
    }
    fail("socket(%d, SOCK_STREAM, IPPROTO_TCP)", family);
  }
  for (i = 0; i < num_tables; i++) {
    struct ipt_table_desc* table = &tables[i];
    strcpy(table->info.name, table->name);
    strcpy(table->replace.name, table->name);
    optlen = sizeof(table->info);
    if (getsockopt(fd, level, IPT_SO_GET_INFO, &table->info, &optlen)) {
      switch (errno) {
      case EPERM:
      case ENOENT:
      case ENOPROTOOPT:
        continue;
      }
      fail("getsockopt(IPT_SO_GET_INFO)");
    }
    if (table->info.size > sizeof(table->replace.entrytable))
      fail("table size is too large: %u", table->info.size);
    if (table->info.num_entries > XT_MAX_ENTRIES)
      fail("too many counters: %u", table->info.num_entries);
    memset(&entries, 0, sizeof(entries));
    strcpy(entries.name, table->name);
    entries.size = table->info.size;
    optlen = sizeof(entries) - sizeof(entries.entrytable) + table->info.size;
    if (getsockopt(fd, level, IPT_SO_GET_ENTRIES, &entries, &optlen))
      fail("getsockopt(IPT_SO_GET_ENTRIES)");
    table->replace.valid_hooks = table->info.valid_hooks;
    table->replace.num_entries = table->info.num_entries;
    table->replace.size = table->info.size;
    memcpy(table->replace.hook_entry, table->info.hook_entry,
           sizeof(table->replace.hook_entry));
    memcpy(table->replace.underflow, table->info.underflow,
           sizeof(table->replace.underflow));
    memcpy(table->replace.entrytable, entries.entrytable, table->info.size);
  }
  close(fd);
}

static void reset_iptables(struct ipt_table_desc* tables, int num_tables,
                           int family, int level)
{
  struct xt_counters counters[XT_MAX_ENTRIES];
  struct ipt_get_entries entries;
  struct ipt_getinfo info;
  socklen_t optlen;
  int fd, i;

  fd = socket(family, SOCK_STREAM, IPPROTO_TCP);
  if (fd == -1) {
    switch (errno) {
    case EAFNOSUPPORT:
    case ENOPROTOOPT:
      return;
    }
    fail("socket(%d, SOCK_STREAM, IPPROTO_TCP)", family);
  }
  for (i = 0; i < num_tables; i++) {
    struct ipt_table_desc* table = &tables[i];
    if (table->info.valid_hooks == 0)
      continue;
    memset(&info, 0, sizeof(info));
    strcpy(info.name, table->name);
    optlen = sizeof(info);
    if (getsockopt(fd, level, IPT_SO_GET_INFO, &info, &optlen))
      fail("getsockopt(IPT_SO_GET_INFO)");
    if (memcmp(&table->info, &info, sizeof(table->info)) == 0) {
      memset(&entries, 0, sizeof(entries));
      strcpy(entries.name, table->name);
      entries.size = table->info.size;
      optlen = sizeof(entries) - sizeof(entries.entrytable) + entries.size;
      if (getsockopt(fd, level, IPT_SO_GET_ENTRIES, &entries, &optlen))
        fail("getsockopt(IPT_SO_GET_ENTRIES)");
      if (memcmp(table->replace.entrytable, entries.entrytable,
                 table->info.size) == 0)
        continue;
    }
    table->replace.num_counters = info.num_entries;
    table->replace.counters = counters;
    optlen = sizeof(table->replace) - sizeof(table->replace.entrytable) +
             table->replace.size;
    if (setsockopt(fd, level, IPT_SO_SET_REPLACE, &table->replace, optlen))
      fail("setsockopt(IPT_SO_SET_REPLACE)");
  }
  close(fd);
}

static void checkpoint_arptables(void)
{
  struct arpt_get_entries entries;
  socklen_t optlen;
  unsigned i;
  int fd;

  fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
  if (fd == -1)
    fail("socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)");
  for (i = 0; i < sizeof(arpt_tables) / sizeof(arpt_tables[0]); i++) {
    struct arpt_table_desc* table = &arpt_tables[i];
    strcpy(table->info.name, table->name);
    strcpy(table->replace.name, table->name);
    optlen = sizeof(table->info);
    if (getsockopt(fd, SOL_IP, ARPT_SO_GET_INFO, &table->info, &optlen)) {
      switch (errno) {
      case EPERM:
      case ENOENT:
      case ENOPROTOOPT:
        continue;
      }
      fail("getsockopt(ARPT_SO_GET_INFO)");
    }
    if (table->info.size > sizeof(table->replace.entrytable))
      fail("table size is too large: %u", table->info.size);
    if (table->info.num_entries > XT_MAX_ENTRIES)
      fail("too many counters: %u", table->info.num_entries);
    memset(&entries, 0, sizeof(entries));
    strcpy(entries.name, table->name);
    entries.size = table->info.size;
    optlen = sizeof(entries) - sizeof(entries.entrytable) + table->info.size;
    if (getsockopt(fd, SOL_IP, ARPT_SO_GET_ENTRIES, &entries, &optlen))
      fail("getsockopt(ARPT_SO_GET_ENTRIES)");
    table->replace.valid_hooks = table->info.valid_hooks;
    table->replace.num_entries = table->info.num_entries;
    table->replace.size = table->info.size;
    memcpy(table->replace.hook_entry, table->info.hook_entry,
           sizeof(table->replace.hook_entry));
    memcpy(table->replace.underflow, table->info.underflow,
           sizeof(table->replace.underflow));
    memcpy(table->replace.entrytable, entries.entrytable, table->info.size);
  }
  close(fd);
}

static void reset_arptables()
{
  struct xt_counters counters[XT_MAX_ENTRIES];
  struct arpt_get_entries entries;
  struct arpt_getinfo info;
  socklen_t optlen;
  unsigned i;
  int fd;

  fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
  if (fd == -1)
    fail("socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)");
  for (i = 0; i < sizeof(arpt_tables) / sizeof(arpt_tables[0]); i++) {
    struct arpt_table_desc* table = &arpt_tables[i];
    if (table->info.valid_hooks == 0)
      continue;
    memset(&info, 0, sizeof(info));
    strcpy(info.name, table->name);
    optlen = sizeof(info);
    if (getsockopt(fd, SOL_IP, ARPT_SO_GET_INFO, &info, &optlen))
      fail("getsockopt(ARPT_SO_GET_INFO)");
    if (memcmp(&table->info, &info, sizeof(table->info)) == 0) {
      memset(&entries, 0, sizeof(entries));
      strcpy(entries.name, table->name);
      entries.size = table->info.size;
      optlen = sizeof(entries) - sizeof(entries.entrytable) + entries.size;
      if (getsockopt(fd, SOL_IP, ARPT_SO_GET_ENTRIES, &entries, &optlen))
        fail("getsockopt(ARPT_SO_GET_ENTRIES)");
      if (memcmp(table->replace.entrytable, entries.entrytable,
                 table->info.size) == 0)
        continue;
    }
    table->replace.num_counters = info.num_entries;
    table->replace.counters = counters;
    optlen = sizeof(table->replace) - sizeof(table->replace.entrytable) +
             table->replace.size;
    if (setsockopt(fd, SOL_IP, ARPT_SO_SET_REPLACE, &table->replace, optlen))
      fail("setsockopt(ARPT_SO_SET_REPLACE)");
  }
  close(fd);
}
#include <linux/if.h>
#include <linux/netfilter_bridge/ebtables.h>

struct ebt_table_desc {
  const char* name;
  struct ebt_replace replace;
  char entrytable[XT_TABLE_SIZE];
};

static struct ebt_table_desc ebt_tables[] = {
    {.name = "filter"}, {.name = "nat"}, {.name = "broute"},
};

static void checkpoint_ebtables(void)
{
  socklen_t optlen;
  unsigned i;
  int fd;

  fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
  if (fd == -1)
    fail("socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)");
  for (i = 0; i < sizeof(ebt_tables) / sizeof(ebt_tables[0]); i++) {
    struct ebt_table_desc* table = &ebt_tables[i];
    strcpy(table->replace.name, table->name);
    optlen = sizeof(table->replace);
    if (getsockopt(fd, SOL_IP, EBT_SO_GET_INIT_INFO, &table->replace,
                   &optlen)) {
      switch (errno) {
      case EPERM:
      case ENOENT:
      case ENOPROTOOPT:
        continue;
      }
      fail("getsockopt(EBT_SO_GET_INIT_INFO)");
    }
    if (table->replace.entries_size > sizeof(table->entrytable))
      fail("table size is too large: %u", table->replace.entries_size);
    table->replace.num_counters = 0;
    table->replace.entries = table->entrytable;
    optlen = sizeof(table->replace) + table->replace.entries_size;
    if (getsockopt(fd, SOL_IP, EBT_SO_GET_INIT_ENTRIES, &table->replace,
                   &optlen))
      fail("getsockopt(EBT_SO_GET_INIT_ENTRIES)");
  }
  close(fd);
}

static void reset_ebtables()
{
  struct ebt_replace replace;
  char entrytable[XT_TABLE_SIZE];
  socklen_t optlen;
  unsigned i, j, h;
  int fd;

  fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
  if (fd == -1)
    fail("socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)");
  for (i = 0; i < sizeof(ebt_tables) / sizeof(ebt_tables[0]); i++) {
    struct ebt_table_desc* table = &ebt_tables[i];
    if (table->replace.valid_hooks == 0)
      continue;
    memset(&replace, 0, sizeof(replace));
    strcpy(replace.name, table->name);
    optlen = sizeof(replace);
    if (getsockopt(fd, SOL_IP, EBT_SO_GET_INFO, &replace, &optlen))
      fail("getsockopt(EBT_SO_GET_INFO)");
    replace.num_counters = 0;
    table->replace.entries = 0;
    for (h = 0; h < NF_BR_NUMHOOKS; h++)
      table->replace.hook_entry[h] = 0;
    if (memcmp(&table->replace, &replace, sizeof(table->replace)) == 0) {
      memset(&entrytable, 0, sizeof(entrytable));
      replace.entries = entrytable;
      optlen = sizeof(replace) + replace.entries_size;
      if (getsockopt(fd, SOL_IP, EBT_SO_GET_ENTRIES, &replace, &optlen))
        fail("getsockopt(EBT_SO_GET_ENTRIES)");
      if (memcmp(table->entrytable, entrytable, replace.entries_size) == 0)
        continue;
    }
    for (j = 0, h = 0; h < NF_BR_NUMHOOKS; h++) {
      if (table->replace.valid_hooks & (1 << h)) {
        table->replace.hook_entry[h] =
            (struct ebt_entries*)table->entrytable + j;
        j++;
      }
    }
    table->replace.entries = table->entrytable;
    optlen = sizeof(table->replace) + table->replace.entries_size;
    if (setsockopt(fd, SOL_IP, EBT_SO_SET_ENTRIES, &table->replace, optlen))
      fail("setsockopt(EBT_SO_SET_ENTRIES)");
  }
  close(fd);
}

static void checkpoint_net_namespace(void)
{
  checkpoint_ebtables();
  checkpoint_arptables();
  checkpoint_iptables(ipv4_tables, sizeof(ipv4_tables) / sizeof(ipv4_tables[0]),
                      AF_INET, SOL_IP);
  checkpoint_iptables(ipv6_tables, sizeof(ipv6_tables) / sizeof(ipv6_tables[0]),
                      AF_INET6, SOL_IPV6);
}

static void reset_net_namespace(void)
{
  reset_ebtables();
  reset_arptables();
  reset_iptables(ipv4_tables, sizeof(ipv4_tables) / sizeof(ipv4_tables[0]),
                 AF_INET, SOL_IP);
  reset_iptables(ipv6_tables, sizeof(ipv6_tables) / sizeof(ipv6_tables[0]),
                 AF_INET6, SOL_IPV6);
}

static void remove_dir(const char* dir)
{
  DIR* dp;
  struct dirent* ep;
  int iter = 0;
retry:
  while (umount2(dir, MNT_DETACH) == 0) {
  }
  dp = opendir(dir);
  if (dp == NULL) {
    if (errno == EMFILE) {
      exitf("opendir(%s) failed due to NOFILE, exiting", dir);
    }
    exitf("opendir(%s) failed", dir);
  }
  while ((ep = readdir(dp))) {
    if (strcmp(ep->d_name, ".") == 0 || strcmp(ep->d_name, "..") == 0)
      continue;
    char filename[FILENAME_MAX];
    snprintf(filename, sizeof(filename), "%s/%s", dir, ep->d_name);
    struct stat st;
    if (lstat(filename, &st))
      exitf("lstat(%s) failed", filename);
    if (S_ISDIR(st.st_mode)) {
      remove_dir(filename);
      continue;
    }
    int i;
    for (i = 0;; i++) {
      if (unlink(filename) == 0)
        break;
      if (errno == EROFS) {
        break;
      }
      if (errno != EBUSY || i > 100)
        exitf("unlink(%s) failed", filename);
      if (umount2(filename, MNT_DETACH))
        exitf("umount(%s) failed", filename);
    }
  }
  closedir(dp);
  int i;
  for (i = 0;; i++) {
    if (rmdir(dir) == 0)
      break;
    if (i < 100) {
      if (errno == EROFS) {
        break;
      }
      if (errno == EBUSY) {
        if (umount2(dir, MNT_DETACH))
          exitf("umount(%s) failed", dir);
        continue;
      }
      if (errno == ENOTEMPTY) {
        if (iter < 100) {
          iter++;
          goto retry;
        }
      }
    }
    exitf("rmdir(%s) failed", dir);
  }
}

static int inject_fault(int nth)
{
  int fd;
  char buf[16];

  fd = open("/proc/thread-self/fail-nth", O_RDWR);
  if (fd == -1)
    exitf("failed to open /proc/thread-self/fail-nth");
  sprintf(buf, "%d", nth + 1);
  if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))
    exitf("failed to write /proc/thread-self/fail-nth");
  return fd;
}

static void execute_one();
extern unsigned long long procid;

static void loop()
{
  checkpoint_net_namespace();
  char cgroupdir[64];
  snprintf(cgroupdir, sizeof(cgroupdir), "/syzcgroup/unified/syz%llu", procid);
  char cgroupdir_cpu[64];
  snprintf(cgroupdir_cpu, sizeof(cgroupdir_cpu), "/syzcgroup/cpu/syz%llu",
           procid);
  char cgroupdir_net[64];
  snprintf(cgroupdir_net, sizeof(cgroupdir_net), "/syzcgroup/net/syz%llu",
           procid);
  if (mkdir(cgroupdir, 0777)) {
  }
  if (mkdir(cgroupdir_cpu, 0777)) {
  }
  if (mkdir(cgroupdir_net, 0777)) {
  }
  int pid = getpid();
  char procs_file[128];
  snprintf(procs_file, sizeof(procs_file), "%s/cgroup.procs", cgroupdir);
  if (!write_file(procs_file, "%d", pid)) {
  }
  snprintf(procs_file, sizeof(procs_file), "%s/cgroup.procs", cgroupdir_cpu);
  if (!write_file(procs_file, "%d", pid)) {
  }
  snprintf(procs_file, sizeof(procs_file), "%s/cgroup.procs", cgroupdir_net);
  if (!write_file(procs_file, "%d", pid)) {
  }
  int iter;
  for (iter = 0;; iter++) {
    char cwdbuf[32];
    sprintf(cwdbuf, "./%d", iter);
    if (mkdir(cwdbuf, 0777))
      fail("failed to mkdir");
    int pid = fork();
    if (pid < 0)
      fail("clone failed");
    if (pid == 0) {
      prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
      setpgrp();
      if (chdir(cwdbuf))
        fail("failed to chdir");
      if (symlink(cgroupdir, "./cgroup")) {
      }
      if (symlink(cgroupdir_cpu, "./cgroup.cpu")) {
      }
      if (symlink(cgroupdir_net, "./cgroup.net")) {
      }
      execute_one();
      doexit(0);
    }

    int status = 0;
    uint64_t start = current_time_ms();
    for (;;) {
      int res = waitpid(-1, &status, __WALL | WNOHANG);
      if (res == pid) {
        break;
      }
      usleep(1000);
      if (current_time_ms() - start < 3 * 1000)
        continue;
      kill(-pid, SIGKILL);
      kill(pid, SIGKILL);
      while (waitpid(-1, &status, __WALL) != pid) {
      }
      break;
    }
    remove_dir(cwdbuf);
    reset_net_namespace();
  }
}

struct thread_t {
  int created, running, call;
  pthread_t th;
};

static struct thread_t threads[16];
static void execute_call(int call);
static int running;

static void* thr(void* arg)
{
  struct thread_t* th = (struct thread_t*)arg;
  for (;;) {
    while (!__atomic_load_n(&th->running, __ATOMIC_ACQUIRE))
      syscall(SYS_futex, &th->running, FUTEX_WAIT, 0, 0);
    execute_call(th->call);
    __atomic_fetch_sub(&running, 1, __ATOMIC_RELAXED);
    __atomic_store_n(&th->running, 0, __ATOMIC_RELEASE);
    syscall(SYS_futex, &th->running, FUTEX_WAKE);
  }
  return 0;
}

static void execute(int num_calls)
{
  int call, thread;
  running = 0;
  for (call = 0; call < num_calls; call++) {
    for (thread = 0; thread < sizeof(threads) / sizeof(threads[0]); thread++) {
      struct thread_t* th = &threads[thread];
      if (!th->created) {
        th->created = 1;
        pthread_attr_t attr;
        pthread_attr_init(&attr);
        pthread_attr_setstacksize(&attr, 128 << 10);
        pthread_create(&th->th, &attr, thr, th);
      }
      if (!__atomic_load_n(&th->running, __ATOMIC_ACQUIRE)) {
        th->call = call;
        __atomic_fetch_add(&running, 1, __ATOMIC_RELAXED);
        __atomic_store_n(&th->running, 1, __ATOMIC_RELEASE);
        syscall(SYS_futex, &th->running, FUTEX_WAKE);
        struct timespec ts;
        ts.tv_sec = 0;
        ts.tv_nsec = 20 * 1000 * 1000;
        syscall(SYS_futex, &th->running, FUTEX_WAIT, 1, &ts);
        if (running)
          usleep((call == num_calls - 1) ? 10000 : 1000);
        break;
      }
    }
  }
}

unsigned long long procid;
void execute_call(int call)
{
  switch (call) {
  case 0:
    memcpy((void*)0x20cb3ff8, "./file0", 8);
    syscall(__NR_mkdir, 0x20cb3ff8, 0);
    break;
  case 1:
    memcpy((void*)0x20cd2ff8, "./file0", 8);
    syscall(__NR_chdir, 0x20cd2ff8);
    break;
  case 2:
    memcpy((void*)0x200012c0, "../file0", 9);
    memcpy((void*)0x200000c0, "./file0", 8);
    syz_fuseblk_mount(0x200012c0, 0x200000c0, 0, 0, 0, 0, 0, 0);
    break;
  case 3:
    memcpy((void*)0x20000100, "../file0", 9);
    write_file("/sys/kernel/debug/failslab/ignore-gfp-wait", "N");
    write_file("/sys/kernel/debug/fail_futex/ignore-private", "N");
    inject_fault(78);
    syz_fuse_mount(0x20000100, 0xc000, 0, 0, 0, 0);
    break;
  }
}

void execute_one()
{
  execute(4);
}

int main()
{
  syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0);
  char* cwd = get_current_dir_name();
  for (procid = 0; procid < 8; procid++) {
    if (fork() == 0) {
      for (;;) {
        if (chdir(cwd))
          fail("failed to chdir");
        use_temporary_dir();
        int pid = do_sandbox_none();
        int status = 0;
        while (waitpid(pid, &status, __WALL) != pid) {
        }
      }
    }
  }
  sleep(1000000);
  return 0;
}