// panic: Unknown syscall 257 error: link should be resolved via Readlink()
// https://syzkaller.appspot.com/bug?id=4253ca83cebbd1069b4b00343e7e4fcad48edde0
// status:fixed
// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE

#include <arpa/inet.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <netinet/in.h>
#include <pthread.h>
#include <sched.h>
#include <setjmp.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/prctl.h>
#include <sys/resource.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

#include <linux/futex.h>
#include <linux/if_addr.h>
#include <linux/if_ether.h>
#include <linux/if_link.h>
#include <linux/if_tun.h>
#include <linux/in6.h>
#include <linux/ip.h>
#include <linux/neighbour.h>
#include <linux/net.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/tcp.h>
#include <linux/veth.h>

unsigned long long procid;

static __thread int skip_segv;
static __thread jmp_buf segv_env;

static void segv_handler(int sig, siginfo_t* info, void* ctx)
{
  uintptr_t addr = (uintptr_t)info->si_addr;
  const uintptr_t prog_start = 1 << 20;
  const uintptr_t prog_end = 100 << 20;
  if (__atomic_load_n(&skip_segv, __ATOMIC_RELAXED) &&
      (addr < prog_start || addr > prog_end)) {
    _longjmp(segv_env, 1);
  }
  exit(sig);
}

static void install_segv_handler(void)
{
  struct sigaction sa;
  memset(&sa, 0, sizeof(sa));
  sa.sa_handler = SIG_IGN;
  syscall(SYS_rt_sigaction, 0x20, &sa, NULL, 8);
  syscall(SYS_rt_sigaction, 0x21, &sa, NULL, 8);
  memset(&sa, 0, sizeof(sa));
  sa.sa_sigaction = segv_handler;
  sa.sa_flags = SA_NODEFER | SA_SIGINFO;
  sigaction(SIGSEGV, &sa, NULL);
  sigaction(SIGBUS, &sa, NULL);
}

#define NONFAILING(...)                                                        \
  {                                                                            \
    __atomic_fetch_add(&skip_segv, 1, __ATOMIC_SEQ_CST);                       \
    if (_setjmp(segv_env) == 0) {                                              \
      __VA_ARGS__;                                                             \
    }                                                                          \
    __atomic_fetch_sub(&skip_segv, 1, __ATOMIC_SEQ_CST);                       \
  }

static void sleep_ms(uint64_t ms)
{
  usleep(ms * 1000);
}

static uint64_t current_time_ms(void)
{
  struct timespec ts;
  if (clock_gettime(CLOCK_MONOTONIC, &ts))
    exit(1);
  return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}

static void use_temporary_dir(void)
{
  char tmpdir_template[] = "./syzkaller.XXXXXX";
  char* tmpdir = mkdtemp(tmpdir_template);
  if (!tmpdir)
    exit(1);
  if (chmod(tmpdir, 0777))
    exit(1);
  if (chdir(tmpdir))
    exit(1);
}

static void thread_start(void* (*fn)(void*), void* arg)
{
  pthread_t th;
  pthread_attr_t attr;
  pthread_attr_init(&attr);
  pthread_attr_setstacksize(&attr, 128 << 10);
  int i;
  for (i = 0; i < 100; i++) {
    if (pthread_create(&th, &attr, fn, arg) == 0) {
      pthread_attr_destroy(&attr);
      return;
    }
    if (errno == EAGAIN) {
      usleep(50);
      continue;
    }
    break;
  }
  exit(1);
}

typedef struct {
  int state;
} event_t;

static void event_init(event_t* ev)
{
  ev->state = 0;
}

static void event_reset(event_t* ev)
{
  ev->state = 0;
}

static void event_set(event_t* ev)
{
  if (ev->state)
    exit(1);
  __atomic_store_n(&ev->state, 1, __ATOMIC_RELEASE);
  syscall(SYS_futex, &ev->state, FUTEX_WAKE | FUTEX_PRIVATE_FLAG);
}

static void event_wait(event_t* ev)
{
  while (!__atomic_load_n(&ev->state, __ATOMIC_ACQUIRE))
    syscall(SYS_futex, &ev->state, FUTEX_WAIT | FUTEX_PRIVATE_FLAG, 0, 0);
}

static int event_isset(event_t* ev)
{
  return __atomic_load_n(&ev->state, __ATOMIC_ACQUIRE);
}

static int event_timedwait(event_t* ev, uint64_t timeout)
{
  uint64_t start = current_time_ms();
  uint64_t now = start;
  for (;;) {
    uint64_t remain = timeout - (now - start);
    struct timespec ts;
    ts.tv_sec = remain / 1000;
    ts.tv_nsec = (remain % 1000) * 1000 * 1000;
    syscall(SYS_futex, &ev->state, FUTEX_WAIT | FUTEX_PRIVATE_FLAG, 0, &ts);
    if (__atomic_load_n(&ev->state, __ATOMIC_RELAXED))
      return 1;
    now = current_time_ms();
    if (now - start > timeout)
      return 0;
  }
}

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 struct {
  char* pos;
  int nesting;
  struct nlattr* nested[8];
  char buf[1024];
} nlmsg;

static void netlink_init(int typ, int flags, const void* data, int size)
{
  memset(&nlmsg, 0, sizeof(nlmsg));
  struct nlmsghdr* hdr = (struct nlmsghdr*)nlmsg.buf;
  hdr->nlmsg_type = typ;
  hdr->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | flags;
  memcpy(hdr + 1, data, size);
  nlmsg.pos = (char*)(hdr + 1) + NLMSG_ALIGN(size);
}

static void netlink_attr(int typ, const void* data, int size)
{
  struct nlattr* attr = (struct nlattr*)nlmsg.pos;
  attr->nla_len = sizeof(*attr) + size;
  attr->nla_type = typ;
  memcpy(attr + 1, data, size);
  nlmsg.pos += NLMSG_ALIGN(attr->nla_len);
}

static void netlink_nest(int typ)
{
  struct nlattr* attr = (struct nlattr*)nlmsg.pos;
  attr->nla_type = typ;
  nlmsg.pos += sizeof(*attr);
  nlmsg.nested[nlmsg.nesting++] = attr;
}

static void netlink_done(void)
{
  struct nlattr* attr = nlmsg.nested[--nlmsg.nesting];
  attr->nla_len = nlmsg.pos - (char*)attr;
}

static int netlink_send(int sock)
{
  if (nlmsg.pos > nlmsg.buf + sizeof(nlmsg.buf) || nlmsg.nesting)
    exit(1);
  struct nlmsghdr* hdr = (struct nlmsghdr*)nlmsg.buf;
  hdr->nlmsg_len = nlmsg.pos - nlmsg.buf;
  struct sockaddr_nl addr;
  memset(&addr, 0, sizeof(addr));
  addr.nl_family = AF_NETLINK;
  unsigned n = sendto(sock, nlmsg.buf, hdr->nlmsg_len, 0,
                      (struct sockaddr*)&addr, sizeof(addr));
  if (n != hdr->nlmsg_len)
    exit(1);
  n = recv(sock, nlmsg.buf, sizeof(nlmsg.buf), 0);
  if (n < sizeof(struct nlmsghdr) + sizeof(struct nlmsgerr))
    exit(1);
  if (hdr->nlmsg_type != NLMSG_ERROR)
    exit(1);
  return -((struct nlmsgerr*)(hdr + 1))->error;
}

static void netlink_add_device_impl(const char* type, const char* name)
{
  struct ifinfomsg hdr;
  memset(&hdr, 0, sizeof(hdr));
  netlink_init(RTM_NEWLINK, NLM_F_EXCL | NLM_F_CREATE, &hdr, sizeof(hdr));
  if (name)
    netlink_attr(IFLA_IFNAME, name, strlen(name));
  netlink_nest(IFLA_LINKINFO);
  netlink_attr(IFLA_INFO_KIND, type, strlen(type));
}

static void netlink_add_device(int sock, const char* type, const char* name)
{
  netlink_add_device_impl(type, name);
  netlink_done();
  int err = netlink_send(sock);
  (void)err;
}

static void netlink_add_veth(int sock, const char* name, const char* peer)
{
  netlink_add_device_impl("veth", name);
  netlink_nest(IFLA_INFO_DATA);
  netlink_nest(VETH_INFO_PEER);
  nlmsg.pos += sizeof(struct ifinfomsg);
  netlink_attr(IFLA_IFNAME, peer, strlen(peer));
  netlink_done();
  netlink_done();
  netlink_done();
  int err = netlink_send(sock);
  (void)err;
}

static void netlink_add_hsr(int sock, const char* name, const char* slave1,
                            const char* slave2)
{
  netlink_add_device_impl("hsr", name);
  netlink_nest(IFLA_INFO_DATA);
  int ifindex1 = if_nametoindex(slave1);
  netlink_attr(IFLA_HSR_SLAVE1, &ifindex1, sizeof(ifindex1));
  int ifindex2 = if_nametoindex(slave2);
  netlink_attr(IFLA_HSR_SLAVE2, &ifindex2, sizeof(ifindex2));
  netlink_done();
  netlink_done();
  int err = netlink_send(sock);
  (void)err;
}

static void netlink_device_change(int sock, const char* name, bool up,
                                  const char* master, const void* mac,
                                  int macsize)
{
  struct ifinfomsg hdr;
  memset(&hdr, 0, sizeof(hdr));
  if (up)
    hdr.ifi_flags = hdr.ifi_change = IFF_UP;
  netlink_init(RTM_NEWLINK, 0, &hdr, sizeof(hdr));
  netlink_attr(IFLA_IFNAME, name, strlen(name));
  if (master) {
    int ifindex = if_nametoindex(master);
    netlink_attr(IFLA_MASTER, &ifindex, sizeof(ifindex));
  }
  if (macsize)
    netlink_attr(IFLA_ADDRESS, mac, macsize);
  int err = netlink_send(sock);
  (void)err;
}

static int netlink_add_addr(int sock, const char* dev, const void* addr,
                            int addrsize)
{
  struct ifaddrmsg hdr;
  memset(&hdr, 0, sizeof(hdr));
  hdr.ifa_family = addrsize == 4 ? AF_INET : AF_INET6;
  hdr.ifa_prefixlen = addrsize == 4 ? 24 : 120;
  hdr.ifa_scope = RT_SCOPE_UNIVERSE;
  hdr.ifa_index = if_nametoindex(dev);
  netlink_init(RTM_NEWADDR, NLM_F_CREATE | NLM_F_REPLACE, &hdr, sizeof(hdr));
  netlink_attr(IFA_LOCAL, addr, addrsize);
  netlink_attr(IFA_ADDRESS, addr, addrsize);
  return netlink_send(sock);
}

static void netlink_add_addr4(int sock, const char* dev, const char* addr)
{
  struct in_addr in_addr;
  inet_pton(AF_INET, addr, &in_addr);
  int err = netlink_add_addr(sock, dev, &in_addr, sizeof(in_addr));
  (void)err;
}

static void netlink_add_addr6(int sock, const char* dev, const char* addr)
{
  struct in6_addr in6_addr;
  inet_pton(AF_INET6, addr, &in6_addr);
  int err = netlink_add_addr(sock, dev, &in6_addr, sizeof(in6_addr));
  (void)err;
}

static void netlink_add_neigh(int sock, const char* name, const void* addr,
                              int addrsize, const void* mac, int macsize)
{
  struct ndmsg hdr;
  memset(&hdr, 0, sizeof(hdr));
  hdr.ndm_family = addrsize == 4 ? AF_INET : AF_INET6;
  hdr.ndm_ifindex = if_nametoindex(name);
  hdr.ndm_state = NUD_PERMANENT;
  netlink_init(RTM_NEWNEIGH, NLM_F_EXCL | NLM_F_CREATE, &hdr, sizeof(hdr));
  netlink_attr(NDA_DST, addr, addrsize);
  netlink_attr(NDA_LLADDR, mac, macsize);
  int err = netlink_send(sock);
  (void)err;
}

static int tunfd = -1;
static int tun_frags_enabled;
#define SYZ_TUN_MAX_PACKET_SIZE 1000

#define TUN_IFACE "syz_tun"

#define LOCAL_MAC 0xaaaaaaaaaaaa
#define REMOTE_MAC 0xaaaaaaaaaabb

#define LOCAL_IPV4 "172.20.20.170"
#define REMOTE_IPV4 "172.20.20.187"

#define LOCAL_IPV6 "fe80::aa"
#define REMOTE_IPV6 "fe80::bb"

#define IFF_NAPI 0x0010
#define IFF_NAPI_FRAGS 0x0020

static void initialize_tun(void)
{
  tunfd = open("/dev/net/tun", O_RDWR | O_NONBLOCK);
  if (tunfd == -1) {
    printf("tun: can't open /dev/net/tun: please enable CONFIG_TUN=y\n");
    printf("otherwise fuzzing or reproducing might not work as intended\n");
    return;
  }
  const int kTunFd = 240;
  if (dup2(tunfd, kTunFd) < 0)
    exit(1);
  close(tunfd);
  tunfd = kTunFd;
  struct ifreq ifr;
  memset(&ifr, 0, sizeof(ifr));
  strncpy(ifr.ifr_name, TUN_IFACE, IFNAMSIZ);
  ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_NAPI | IFF_NAPI_FRAGS;
  if (ioctl(tunfd, TUNSETIFF, (void*)&ifr) < 0) {
    ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
    if (ioctl(tunfd, TUNSETIFF, (void*)&ifr) < 0)
      exit(1);
  }
  if (ioctl(tunfd, TUNGETIFF, (void*)&ifr) < 0)
    exit(1);
  tun_frags_enabled = (ifr.ifr_flags & IFF_NAPI_FRAGS) != 0;
  char sysctl[64];
  sprintf(sysctl, "/proc/sys/net/ipv6/conf/%s/accept_dad", TUN_IFACE);
  write_file(sysctl, "0");
  sprintf(sysctl, "/proc/sys/net/ipv6/conf/%s/router_solicitations", TUN_IFACE);
  write_file(sysctl, "0");
  int sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
  if (sock == -1)
    exit(1);
  netlink_add_addr4(sock, TUN_IFACE, LOCAL_IPV4);
  netlink_add_addr6(sock, TUN_IFACE, LOCAL_IPV6);
  uint64_t macaddr = REMOTE_MAC;
  struct in_addr in_addr;
  inet_pton(AF_INET, REMOTE_IPV4, &in_addr);
  netlink_add_neigh(sock, TUN_IFACE, &in_addr, sizeof(in_addr), &macaddr,
                    ETH_ALEN);
  struct in6_addr in6_addr;
  inet_pton(AF_INET6, REMOTE_IPV6, &in6_addr);
  netlink_add_neigh(sock, TUN_IFACE, &in6_addr, sizeof(in6_addr), &macaddr,
                    ETH_ALEN);
  macaddr = LOCAL_MAC;
  netlink_device_change(sock, TUN_IFACE, true, 0, &macaddr, ETH_ALEN);
  close(sock);
}

#define DEV_IPV4 "172.20.20.%d"
#define DEV_IPV6 "fe80::%02x"
#define DEV_MAC 0x00aaaaaaaaaa
static void initialize_netdevices(void)
{
  char netdevsim[16];
  sprintf(netdevsim, "netdevsim%d", (int)procid);
  struct {
    const char* type;
    const char* dev;
  } devtypes[] = {
      {"ip6gretap", "ip6gretap0"}, {"bridge", "bridge0"},
      {"vcan", "vcan0"},           {"bond", "bond0"},
      {"team", "team0"},           {"dummy", "dummy0"},
      {"nlmon", "nlmon0"},         {"caif", "caif0"},
      {"batadv", "batadv0"},       {"vxcan", "vxcan1"},
      {"netdevsim", netdevsim},    {"veth", 0},
  };
  const char* devmasters[] = {"bridge", "bond", "team"};
  struct {
    const char* name;
    int macsize;
    bool noipv6;
  } devices[] = {
      {"lo", ETH_ALEN},
      {"sit0", 0},
      {"bridge0", ETH_ALEN},
      {"vcan0", 0, true},
      {"tunl0", 0},
      {"gre0", 0},
      {"gretap0", ETH_ALEN},
      {"ip_vti0", 0},
      {"ip6_vti0", 0},
      {"ip6tnl0", 0},
      {"ip6gre0", 0},
      {"ip6gretap0", ETH_ALEN},
      {"erspan0", ETH_ALEN},
      {"bond0", ETH_ALEN},
      {"veth0", ETH_ALEN},
      {"veth1", ETH_ALEN},
      {"team0", ETH_ALEN},
      {"veth0_to_bridge", ETH_ALEN},
      {"veth1_to_bridge", ETH_ALEN},
      {"veth0_to_bond", ETH_ALEN},
      {"veth1_to_bond", ETH_ALEN},
      {"veth0_to_team", ETH_ALEN},
      {"veth1_to_team", ETH_ALEN},
      {"veth0_to_hsr", ETH_ALEN},
      {"veth1_to_hsr", ETH_ALEN},
      {"hsr0", 0},
      {"dummy0", ETH_ALEN},
      {"nlmon0", 0},
      {"vxcan1", 0, true},
      {"caif0", ETH_ALEN},
      {"batadv0", ETH_ALEN},
      {netdevsim, ETH_ALEN},
  };
  int sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
  if (sock == -1)
    exit(1);
  unsigned i;
  for (i = 0; i < sizeof(devtypes) / sizeof(devtypes[0]); i++)
    netlink_add_device(sock, devtypes[i].type, devtypes[i].dev);
  for (i = 0; i < sizeof(devmasters) / (sizeof(devmasters[0])); i++) {
    char master[32], slave0[32], veth0[32], slave1[32], veth1[32];
    sprintf(slave0, "%s_slave_0", devmasters[i]);
    sprintf(veth0, "veth0_to_%s", devmasters[i]);
    netlink_add_veth(sock, slave0, veth0);
    sprintf(slave1, "%s_slave_1", devmasters[i]);
    sprintf(veth1, "veth1_to_%s", devmasters[i]);
    netlink_add_veth(sock, slave1, veth1);
    sprintf(master, "%s0", devmasters[i]);
    netlink_device_change(sock, slave0, false, master, 0, 0);
    netlink_device_change(sock, slave1, false, master, 0, 0);
  }
  netlink_device_change(sock, "bridge_slave_0", true, 0, 0, 0);
  netlink_device_change(sock, "bridge_slave_1", true, 0, 0, 0);
  netlink_add_veth(sock, "hsr_slave_0", "veth0_to_hsr");
  netlink_add_veth(sock, "hsr_slave_1", "veth1_to_hsr");
  netlink_add_hsr(sock, "hsr0", "hsr_slave_0", "hsr_slave_1");
  netlink_device_change(sock, "hsr_slave_0", true, 0, 0, 0);
  netlink_device_change(sock, "hsr_slave_1", true, 0, 0, 0);
  for (i = 0; i < sizeof(devices) / (sizeof(devices[0])); i++) {
    char addr[32];
    sprintf(addr, DEV_IPV4, i + 10);
    netlink_add_addr4(sock, devices[i].name, addr);
    if (!devices[i].noipv6) {
      sprintf(addr, DEV_IPV6, i + 10);
      netlink_add_addr6(sock, devices[i].name, addr);
    }
    uint64_t macaddr = DEV_MAC + ((i + 10ull) << 40);
    netlink_device_change(sock, devices[i].name, true, 0, &macaddr,
                          devices[i].macsize);
  }
  close(sock);
}
static void initialize_netdevices_init(void)
{
  int sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
  if (sock == -1)
    exit(1);
  struct {
    const char* type;
    int macsize;
    bool noipv6;
    bool noup;
  } devtypes[] = {
      {"nr", 7, true},
      {"rose", 5, true, true},
  };
  unsigned i;
  for (i = 0; i < sizeof(devtypes) / sizeof(devtypes[0]); i++) {
    char dev[32], addr[32];
    sprintf(dev, "%s%d", devtypes[i].type, (int)procid);
    sprintf(addr, "172.30.%d.%d", i, (int)procid + 1);
    netlink_add_addr4(sock, dev, addr);
    if (!devtypes[i].noipv6) {
      sprintf(addr, "fe88::%02x:%02x", i, (int)procid + 1);
      netlink_add_addr6(sock, dev, addr);
    }
    int macsize = devtypes[i].macsize;
    uint64_t macaddr = 0xbbbbbb +
                       ((unsigned long long)i << (8 * (macsize - 2))) +
                       (procid << (8 * (macsize - 1)));
    netlink_device_change(sock, dev, !devtypes[i].noup, 0, &macaddr, macsize);
  }
  close(sock);
}

static void setup_common()
{
  if (mount(0, "/sys/fs/fuse/connections", "fusectl", 0, 0)) {
  }
}

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 = (200 << 20);
  setrlimit(RLIMIT_AS, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 32 << 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);
  rlim.rlim_cur = rlim.rlim_max = 256;
  setrlimit(RLIMIT_NOFILE, &rlim);
  if (unshare(CLONE_NEWNS)) {
  }
  if (unshare(CLONE_NEWIPC)) {
  }
  if (unshare(0x02000000)) {
  }
  if (unshare(CLONE_NEWUTS)) {
  }
  if (unshare(CLONE_SYSVSEM)) {
  }
  typedef struct {
    const char* name;
    const char* value;
  } sysctl_t;
  static const sysctl_t sysctls[] = {
      {"/proc/sys/kernel/shmmax", "16777216"},
      {"/proc/sys/kernel/shmall", "536870912"},
      {"/proc/sys/kernel/shmmni", "1024"},
      {"/proc/sys/kernel/msgmax", "8192"},
      {"/proc/sys/kernel/msgmni", "1024"},
      {"/proc/sys/kernel/msgmnb", "1024"},
      {"/proc/sys/kernel/sem", "1024 1048576 500 1024"},
  };
  unsigned i;
  for (i = 0; i < sizeof(sysctls) / sizeof(sysctls[0]); i++)
    write_file(sysctls[i].name, sysctls[i].value);
}

int wait_for_loop(int pid)
{
  if (pid < 0)
    exit(1);
  int status = 0;
  while (waitpid(-1, &status, __WALL) != pid) {
  }
  return WEXITSTATUS(status);
}

static int do_sandbox_none(void)
{
  if (unshare(CLONE_NEWPID)) {
  }
  int pid = fork();
  if (pid != 0)
    return wait_for_loop(pid);
  setup_common();
  sandbox_common();
  initialize_netdevices_init();
  if (unshare(CLONE_NEWNET)) {
  }
  initialize_tun();
  initialize_netdevices();
  loop();
  exit(1);
}

static void close_fds()
{
  int fd;
  for (fd = 3; fd < 30; fd++)
    close(fd);
}

static void setup_binfmt_misc()
{
  if (mount(0, "/proc/sys/fs/binfmt_misc", "binfmt_misc", 0, 0)) {
  }
  write_file("/proc/sys/fs/binfmt_misc/register", ":syz0:M:0:\x01::./file0:");
  write_file("/proc/sys/fs/binfmt_misc/register",
             ":syz1:M:1:\x02::./file0:POC");
}

struct thread_t {
  int created, call;
  event_t ready, done;
};

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 (;;) {
    event_wait(&th->ready);
    event_reset(&th->ready);
    execute_call(th->call);
    __atomic_fetch_sub(&running, 1, __ATOMIC_RELAXED);
    event_set(&th->done);
  }
  return 0;
}

static void loop(void)
{
  int i, call, thread;
  int collide = 0;
again:
  for (call = 0; call < 3; call++) {
    for (thread = 0; thread < (int)(sizeof(threads) / sizeof(threads[0]));
         thread++) {
      struct thread_t* th = &threads[thread];
      if (!th->created) {
        th->created = 1;
        event_init(&th->ready);
        event_init(&th->done);
        event_set(&th->done);
        thread_start(thr, th);
      }
      if (!event_isset(&th->done))
        continue;
      event_reset(&th->done);
      th->call = call;
      __atomic_fetch_add(&running, 1, __ATOMIC_RELAXED);
      event_set(&th->ready);
      if (collide && (call % 2) == 0)
        break;
      event_timedwait(&th->done, 45);
      break;
    }
  }
  for (i = 0; i < 100 && __atomic_load_n(&running, __ATOMIC_RELAXED); i++)
    sleep_ms(1);
  close_fds();
  if (!collide) {
    collide = 1;
    goto again;
  }
}

void execute_call(int call)
{
  switch (call) {
  case 0:
    syscall(__NR_open, 0, 0, 0x10);
    break;
  case 1:
    NONFAILING(memcpy((void*)0x200000c0, "./file1\000", 8));
    syscall(__NR_openat, 0xffffffffffffff9c, 0x200000c0, 0x40, 0x16);
    break;
  case 2:
    NONFAILING(memcpy((void*)0x20000040, "./file1/file0\000", 14));
    NONFAILING(memcpy((void*)0x20000080, "./file1\000", 8));
    syscall(__NR_symlink, 0x20000040, 0x20000080);
    break;
  }
}
int main(void)
{
  syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0);
  setup_binfmt_misc();
  install_segv_handler();
  use_temporary_dir();
  do_sandbox_none();
  return 0;
}