// https://syzkaller.appspot.com/bug?id=8af2597890938b642c3bf44a85859691fb9d5cfa
// autogenerated by syzkaller (http://github.com/google/syzkaller)

#define _GNU_SOURCE
#include <arpa/inet.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/if.h>
#include <linux/if_ether.h>
#include <linux/if_tun.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <net/if_arp.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/uio.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 <setjmp.h>
#include <signal.h>
#include <stdarg.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.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 __thread int skip_segv;
static __thread jmp_buf segv_env;

static void segv_handler(int sig, siginfo_t* info, void* uctx)
{
  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);
  }
  doexit(sig);
}

static void install_segv_handler()
{
  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 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 void vsnprintf_check(char* str, size_t size, const char* format,
                            va_list args)
{
  int rv;

  rv = vsnprintf(str, size, format, args);
  if (rv < 0)
    fail("tun: snprintf failed");
  if ((size_t)rv >= size)
    fail("tun: string '%s...' doesn't fit into buffer", str);
}

static void snprintf_check(char* str, size_t size, const char* format, ...)
{
  va_list args;

  va_start(args, format);
  vsnprintf_check(str, size, format, args);
  va_end(args);
}

#define COMMAND_MAX_LEN 128
#define PATH_PREFIX                                                            \
  "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin "
#define PATH_PREFIX_LEN (sizeof(PATH_PREFIX) - 1)

static void execute_command(bool panic, const char* format, ...)
{
  va_list args;
  char command[PATH_PREFIX_LEN + COMMAND_MAX_LEN];
  int rv;

  va_start(args, format);
  memcpy(command, PATH_PREFIX, PATH_PREFIX_LEN);
  vsnprintf_check(command + PATH_PREFIX_LEN, COMMAND_MAX_LEN, format, args);
  rv = system(command);
  if (panic && rv != 0)
    fail("tun: command \"%s\" failed with code %d", &command[0], rv);

  va_end(args);
}

static int tunfd = -1;
static int tun_frags_enabled;

#define SYZ_TUN_MAX_PACKET_SIZE 1000

#define TUN_IFACE "syz_tun"

#define LOCAL_MAC "aa:aa:aa:aa:aa:aa"
#define REMOTE_MAC "aa:aa:aa:aa:aa:bb"

#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 = 252;
  if (dup2(tunfd, kTunFd) < 0)
    fail("dup2(tunfd, kTunFd) failed");
  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)
      fail("tun: ioctl(TUNSETIFF) failed");
  }
  if (ioctl(tunfd, TUNGETIFF, (void*)&ifr) < 0)
    fail("tun: ioctl(TUNGETIFF) failed");
  tun_frags_enabled = (ifr.ifr_flags & IFF_NAPI_FRAGS) != 0;

  execute_command(1, "sysctl -w net.ipv6.conf.%s.accept_dad=0", TUN_IFACE);

  execute_command(1, "sysctl -w net.ipv6.conf.%s.router_solicitations=0",
                  TUN_IFACE);

  execute_command(1, "ip link set dev %s address %s", TUN_IFACE, LOCAL_MAC);
  execute_command(1, "ip addr add %s/24 dev %s", LOCAL_IPV4, TUN_IFACE);
  execute_command(1, "ip -6 addr add %s/120 dev %s", LOCAL_IPV6, TUN_IFACE);
  execute_command(1, "ip neigh add %s lladdr %s dev %s nud permanent",
                  REMOTE_IPV4, REMOTE_MAC, TUN_IFACE);
  execute_command(1, "ip -6 neigh add %s lladdr %s dev %s nud permanent",
                  REMOTE_IPV6, REMOTE_MAC, TUN_IFACE);
  execute_command(1, "ip link set dev %s up", TUN_IFACE);
}

#define DEV_IPV4 "172.20.20.%d"
#define DEV_IPV6 "fe80::%02hx"
#define DEV_MAC "aa:aa:aa:aa:aa:%02hx"

static void initialize_netdevices(void)
{
  unsigned i;
  const char* devtypes[] = {"ip6gretap", "bridge", "vcan", "bond", "veth"};
  const char* devnames[] = {"lo",       "sit0",    "bridge0", "vcan0",
                            "tunl0",    "gre0",    "gretap0", "ip_vti0",
                            "ip6_vti0", "ip6tnl0", "ip6gre0", "ip6gretap0",
                            "erspan0",  "bond0",   "veth0",   "veth1"};

  for (i = 0; i < sizeof(devtypes) / (sizeof(devtypes[0])); i++)
    execute_command(0, "ip link add dev %s0 type %s", devtypes[i], devtypes[i]);
  execute_command(0, "ip link add dev veth1 type veth");
  for (i = 0; i < sizeof(devnames) / (sizeof(devnames[0])); i++) {
    char addr[32];
    snprintf_check(addr, sizeof(addr), DEV_IPV4, i + 10);
    execute_command(0, "ip -4 addr add %s/24 dev %s", addr, devnames[i]);
    snprintf_check(addr, sizeof(addr), DEV_IPV6, i + 10);
    execute_command(0, "ip -6 addr add %s/120 dev %s", addr, devnames[i]);
    snprintf_check(addr, sizeof(addr), DEV_MAC, i + 10);
    execute_command(0, "ip link set dev %s address %s", devnames[i], addr);
    execute_command(0, "ip link set dev %s up", devnames[i]);
  }
}

#define MAX_FRAGS 4
struct vnet_fragmentation {
  uint32_t full;
  uint32_t count;
  uint32_t frags[MAX_FRAGS];
};

static uintptr_t syz_emit_ethernet(uintptr_t a0, uintptr_t a1, uintptr_t a2)
{
  if (tunfd < 0)
    return (uintptr_t)-1;

  uint32_t length = a0;
  char* data = (char*)a1;

  struct vnet_fragmentation* frags = (struct vnet_fragmentation*)a2;
  struct iovec vecs[MAX_FRAGS + 1];
  uint32_t nfrags = 0;
  if (!tun_frags_enabled || frags == NULL) {
    vecs[nfrags].iov_base = data;
    vecs[nfrags].iov_len = length;
    nfrags++;
  } else {
    bool full = true;
    uint32_t i, count = 0;
    NONFAILING(full = frags->full);
    NONFAILING(count = frags->count);
    if (count > MAX_FRAGS)
      count = MAX_FRAGS;
    for (i = 0; i < count && length != 0; i++) {
      uint32_t size = 0;
      NONFAILING(size = frags->frags[i]);
      if (size > length)
        size = length;
      vecs[nfrags].iov_base = data;
      vecs[nfrags].iov_len = size;
      nfrags++;
      data += size;
      length -= size;
    }
    if (length != 0 && (full || nfrags == 0)) {
      vecs[nfrags].iov_base = data;
      vecs[nfrags].iov_len = length;
      nfrags++;
    }
  }
  return writev(tunfd, vecs, nfrags);
}

uint64_t r[2] = {0xffffffffffffffff, 0xffffffffffffffff};
void loop()
{
  long res;
  res = syscall(__NR_socket, 0xa, 2, 0);
  if (res != -1)
    r[0] = res;
  res = syscall(__NR_socket, 0x18, 1, 1);
  if (res != -1)
    r[1] = res;
  NONFAILING(*(uint16_t*)0x205fafd2 = 0x18);
  NONFAILING(*(uint32_t*)0x205fafd4 = 1);
  NONFAILING(*(uint32_t*)0x205fafd8 = 0);
  NONFAILING(*(uint32_t*)0x205fafdc = r[0]);
  NONFAILING(*(uint16_t*)0x205fafe0 = 2);
  NONFAILING(*(uint16_t*)0x205fafe2 = htobe16(0x4e21));
  NONFAILING(*(uint8_t*)0x205fafe4 = 0xac);
  NONFAILING(*(uint8_t*)0x205fafe5 = 0x14);
  NONFAILING(*(uint8_t*)0x205fafe6 = 0);
  NONFAILING(*(uint8_t*)0x205fafe7 = 0xbb);
  NONFAILING(*(uint8_t*)0x205fafe8 = 0);
  NONFAILING(*(uint8_t*)0x205fafe9 = 0);
  NONFAILING(*(uint8_t*)0x205fafea = 0);
  NONFAILING(*(uint8_t*)0x205fafeb = 0);
  NONFAILING(*(uint8_t*)0x205fafec = 0);
  NONFAILING(*(uint8_t*)0x205fafed = 0);
  NONFAILING(*(uint8_t*)0x205fafee = 0);
  NONFAILING(*(uint8_t*)0x205fafef = 0);
  NONFAILING(*(uint32_t*)0x205faff0 = 4);
  NONFAILING(*(uint32_t*)0x205faff4 = 0);
  NONFAILING(*(uint32_t*)0x205faff8 = 2);
  NONFAILING(*(uint32_t*)0x205faffc = 0);
  syscall(__NR_connect, r[1], 0x205fafd2, 0x2e);
  NONFAILING(*(uint16_t*)0x200000c0 = 0xa);
  NONFAILING(*(uint16_t*)0x200000c2 = htobe16(0x4e21));
  NONFAILING(*(uint32_t*)0x200000c4 = 0x7fff);
  NONFAILING(*(uint8_t*)0x200000c8 = 0);
  NONFAILING(*(uint8_t*)0x200000c9 = 0);
  NONFAILING(*(uint8_t*)0x200000ca = 0);
  NONFAILING(*(uint8_t*)0x200000cb = 0);
  NONFAILING(*(uint8_t*)0x200000cc = 0);
  NONFAILING(*(uint8_t*)0x200000cd = 0);
  NONFAILING(*(uint8_t*)0x200000ce = 0);
  NONFAILING(*(uint8_t*)0x200000cf = 0);
  NONFAILING(*(uint8_t*)0x200000d0 = 0);
  NONFAILING(*(uint8_t*)0x200000d1 = 0);
  NONFAILING(*(uint8_t*)0x200000d2 = -1);
  NONFAILING(*(uint8_t*)0x200000d3 = -1);
  NONFAILING(*(uint8_t*)0x200000d4 = 0xac);
  NONFAILING(*(uint8_t*)0x200000d5 = 0x14);
  NONFAILING(*(uint8_t*)0x200000d6 = 0x14);
  NONFAILING(*(uint8_t*)0x200000d7 = 0xaa);
  NONFAILING(*(uint32_t*)0x200000d8 = 3);
  syscall(__NR_connect, r[0], 0x200000c0, 0x1c);
  NONFAILING(*(uint16_t*)0x200021c0 = 0x18);
  NONFAILING(*(uint32_t*)0x200021c2 = 0);
  NONFAILING(*(uint16_t*)0x200021c6 = 0);
  NONFAILING(*(uint8_t*)0x200021c8 = 0);
  NONFAILING(*(uint8_t*)0x200021c9 = 0);
  NONFAILING(*(uint8_t*)0x200021ca = 0);
  NONFAILING(*(uint8_t*)0x200021cb = 0);
  NONFAILING(*(uint8_t*)0x200021cc = 0);
  NONFAILING(*(uint8_t*)0x200021cd = 0);
  NONFAILING(memcpy(
      (void*)0x200021ce,
      "\x69\x66\x62\x30\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", 16));
  syscall(__NR_sendto, r[1], 0x20001180, 0, 0x40001, 0x200021c0, 0x80);
  NONFAILING(*(uint32_t*)0x20001780 = 0);
  NONFAILING(*(uint32_t*)0x20001784 = 0);
  NONFAILING(*(uint32_t*)0x20001788 = 0);
  NONFAILING(*(uint32_t*)0x2000178c = 0);
  NONFAILING(*(uint32_t*)0x20001790 = 0);
  NONFAILING(*(uint32_t*)0x20001794 = 0);
  syz_emit_ethernet(1, 0x20000700, 0x20001780);
}

int main()
{
  syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0);
  install_segv_handler();
  use_temporary_dir();
  initialize_tun();
  initialize_netdevices();
  loop();
  return 0;
}