text: // WARNING: lock held when returning to user space! (2)
  // https://syzkaller.appspot.com/bug?id=9eafbcd9d32e89e77005c59b23c0768e7ae9c756
  // status:fixed
  // autogenerated by syzkaller (http://github.com/google/syzkaller)
  
  #define _GNU_SOURCE
  #include <arpa/inet.h>
  #include <endian.h>
  #include <errno.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 <sched.h>
  #include <signal.h>
  #include <stdarg.h>
  #include <stdarg.h>
  #include <stdbool.h>
  #include <stdbool.h>
  #include <stdio.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <sys/ioctl.h>
  #include <sys/prctl.h>
  #include <sys/resource.h>
  #include <sys/stat.h>
  #include <sys/syscall.h>
  #include <sys/time.h>
  #include <sys/uio.h>
  #include <sys/wait.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 <string.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);
  }
  
  #define BITMASK_LEN(type, bf_len) (type)((1ull << (bf_len)) - 1)
  
  #define BITMASK_LEN_OFF(type, bf_off, bf_len)                                  \
    (type)(BITMASK_LEN(type, (bf_len)) << (bf_off))
  
  #define STORE_BY_BITMASK(type, addr, val, bf_off, bf_len)                      \
    if ((bf_off) == 0 && (bf_len) == 0) {                                        \
      *(type*)(addr) = (type)(val);                                              \
    } else {                                                                     \
      type new_val = *(type*)(addr);                                             \
      new_val &= ~BITMASK_LEN_OFF(type, (bf_off), (bf_len));                     \
      new_val |= ((type)(val)&BITMASK_LEN(type, (bf_len))) << (bf_off);          \
      *(type*)(addr) = new_val;                                                  \
    }
  
  struct csum_inet {
    uint32_t acc;
  };
  
  static void csum_inet_init(struct csum_inet* csum)
  {
    csum->acc = 0;
  }
  
  static void csum_inet_update(struct csum_inet* csum, const uint8_t* data,
                               size_t length)
  {
    if (length == 0)
      return;
  
    size_t i;
    for (i = 0; i < length - 1; i += 2)
      csum->acc += *(uint16_t*)&data[i];
  
    if (length & 1)
      csum->acc += (uint16_t)data[length - 1];
  
    while (csum->acc > 0xffff)
      csum->acc = (csum->acc & 0xffff) + (csum->acc >> 16);
  }
  
  static uint16_t csum_inet_digest(struct csum_inet* csum)
  {
    return ~csum->acc;
  }
  
  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);
    va_end(args);
    rv = system(command);
    if (rv) {
      if (panic)
        fail("command '%s' failed: %d", &command[0], rv);
    }
  }
  
  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", "team"};
    const char* devnames[] = {"lo",
                              "sit0",
                              "bridge0",
                              "vcan0",
                              "tunl0",
                              "gre0",
                              "gretap0",
                              "ip_vti0",
                              "ip6_vti0",
                              "ip6tnl0",
                              "ip6gre0",
                              "ip6gretap0",
                              "erspan0",
                              "bond0",
                              "veth0",
                              "veth1",
                              "team0",
                              "veth0_to_bridge",
                              "veth1_to_bridge",
                              "veth0_to_bond",
                              "veth1_to_bond",
                              "veth0_to_team",
                              "veth1_to_team"};
    const char* devmasters[] = {"bridge", "bond", "team"};
  
    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 type veth");
  
    for (i = 0; i < sizeof(devmasters) / (sizeof(devmasters[0])); i++) {
      execute_command(
          0, "ip link add name %s_slave_0 type veth peer name veth0_to_%s",
          devmasters[i], devmasters[i]);
      execute_command(
          0, "ip link add name %s_slave_1 type veth peer name veth1_to_%s",
          devmasters[i], devmasters[i]);
      execute_command(0, "ip link set %s_slave_0 master %s0", devmasters[i],
                      devmasters[i]);
      execute_command(0, "ip link set %s_slave_1 master %s0", devmasters[i],
                      devmasters[i]);
      execute_command(0, "ip link set veth0_to_%s up", devmasters[i]);
      execute_command(0, "ip link set veth1_to_%s up", devmasters[i]);
    }
    execute_command(0, "ip link set bridge_slave_0 up");
    execute_command(0, "ip link set bridge_slave_1 up");
  
    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;
      full = frags->full;
      count = frags->count;
      if (count > MAX_FRAGS)
        count = MAX_FRAGS;
      for (i = 0; i < count && length != 0; i++) {
        uint32_t size = 0;
        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);
  }
  
  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;
  
    sandbox_common();
    if (unshare(CLONE_NEWNET)) {
    }
    initialize_tun();
    initialize_netdevices();
  
    loop();
    doexit(1);
  }
  
  uint64_t r[1] = {0xffffffffffffffff};
  void loop()
  {
    long res = 0;
    memcpy((void*)0x20000000, "\xcd\xbf\x0e\x00\x00\x84", 6);
    *(uint8_t*)0x20000006 = -1;
    *(uint8_t*)0x20000007 = -1;
    *(uint8_t*)0x20000008 = -1;
    *(uint8_t*)0x20000009 = -1;
    *(uint8_t*)0x2000000a = -1;
    *(uint8_t*)0x2000000b = -1;
    *(uint16_t*)0x2000000c = htobe16(0x86dd);
    STORE_BY_BITMASK(uint8_t, 0x2000000e, 0, 0, 4);
    STORE_BY_BITMASK(uint8_t, 0x2000000e, 6, 4, 4);
    memcpy((void*)0x2000000f, "\x02\x29\x0f", 3);
    *(uint16_t*)0x20000012 = htobe16(0x38);
    *(uint8_t*)0x20000014 = 0x3a;
    *(uint8_t*)0x20000015 = 0;
    *(uint8_t*)0x20000016 = 0xfe;
    *(uint8_t*)0x20000017 = 0x80;
    *(uint8_t*)0x20000018 = 0;
    *(uint8_t*)0x20000019 = 0;
    *(uint8_t*)0x2000001a = 0;
    *(uint8_t*)0x2000001b = 0;
    *(uint8_t*)0x2000001c = 0;
    *(uint8_t*)0x2000001d = 0;
    *(uint8_t*)0x2000001e = 0;
    *(uint8_t*)0x2000001f = 0;
    *(uint8_t*)0x20000020 = 0;
    *(uint8_t*)0x20000021 = 0;
    *(uint8_t*)0x20000022 = 0;
    *(uint8_t*)0x20000023 = 0;
    *(uint8_t*)0x20000024 = 0;
    *(uint8_t*)0x20000025 = 0;
    *(uint8_t*)0x20000026 = -1;
    *(uint8_t*)0x20000027 = 2;
    *(uint8_t*)0x20000028 = 0;
    *(uint8_t*)0x20000029 = 0;
    *(uint8_t*)0x2000002a = 0;
    *(uint8_t*)0x2000002b = 0;
    *(uint8_t*)0x2000002c = 0;
    *(uint8_t*)0x2000002d = 0;
    *(uint8_t*)0x2000002e = 0;
    *(uint8_t*)0x2000002f = 0;
    *(uint8_t*)0x20000030 = 0;
    *(uint8_t*)0x20000031 = 0;
    *(uint8_t*)0x20000032 = 0;
    *(uint8_t*)0x20000033 = 0;
    *(uint8_t*)0x20000034 = 0;
    *(uint8_t*)0x20000035 = 1;
    *(uint8_t*)0x20000036 = 2;
    *(uint8_t*)0x20000037 = 0;
    *(uint16_t*)0x20000038 = 0;
    *(uint32_t*)0x2000003a = htobe32(0);
    STORE_BY_BITMASK(uint8_t, 0x2000003e, 0, 0, 4);
    STORE_BY_BITMASK(uint8_t, 0x2000003e, 6, 4, 4);
    memcpy((void*)0x2000003f, "\x94\x33\xdf", 3);
    *(uint16_t*)0x20000042 = htobe16(0);
    *(uint8_t*)0x20000044 = 0x3a;
    *(uint8_t*)0x20000045 = 0;
    *(uint64_t*)0x20000046 = htobe64(0);
    *(uint64_t*)0x2000004e = htobe64(1);
    *(uint8_t*)0x20000056 = 0xfe;
    *(uint8_t*)0x20000057 = 0x80;
    *(uint8_t*)0x20000058 = 0;
    *(uint8_t*)0x20000059 = 0;
    *(uint8_t*)0x2000005a = 0;
    *(uint8_t*)0x2000005b = 0;
    *(uint8_t*)0x2000005c = 0;
    *(uint8_t*)0x2000005d = 0;
    *(uint8_t*)0x2000005e = 0;
    *(uint8_t*)0x2000005f = 0;
    *(uint8_t*)0x20000060 = 0;
    *(uint8_t*)0x20000061 = 0;
    *(uint8_t*)0x20000062 = 0;
    *(uint8_t*)0x20000063 = 0;
    *(uint8_t*)0x20000064 = 0;
    *(uint8_t*)0x20000065 = 0;
    memcpy((void*)0x20000066, "\x80\x00\x00\xe7\x7f\x00\x04\x00", 8);
    struct csum_inet csum_1;
    csum_inet_init(&csum_1);
    csum_inet_update(&csum_1, (const uint8_t*)0x20000016, 16);
    csum_inet_update(&csum_1, (const uint8_t*)0x20000026, 16);
    uint32_t csum_1_chunk_2 = 0x38000000;
    csum_inet_update(&csum_1, (const uint8_t*)&csum_1_chunk_2, 4);
    uint32_t csum_1_chunk_3 = 0x3a000000;
    csum_inet_update(&csum_1, (const uint8_t*)&csum_1_chunk_3, 4);
    csum_inet_update(&csum_1, (const uint8_t*)0x20000036, 56);
    *(uint16_t*)0x20000038 = csum_inet_digest(&csum_1);
    syz_emit_ethernet(0x6e, 0x20000000, 0);
    res = syscall(__NR_socket, 0xa, 1, 0);
    if (res != -1)
      r[0] = res;
    *(uint8_t*)0x200001c0 = 0xfe;
    *(uint8_t*)0x200001c1 = 0x80;
    *(uint8_t*)0x200001c2 = 0;
    *(uint8_t*)0x200001c3 = 0;
    *(uint8_t*)0x200001c4 = 0;
    *(uint8_t*)0x200001c5 = 0;
    *(uint8_t*)0x200001c6 = 0;
    *(uint8_t*)0x200001c7 = 0;
    *(uint8_t*)0x200001c8 = 0;
    *(uint8_t*)0x200001c9 = 0;
    *(uint8_t*)0x200001ca = 0;
    *(uint8_t*)0x200001cb = 0;
    *(uint8_t*)0x200001cc = 0;
    *(uint8_t*)0x200001cd = 0;
    *(uint8_t*)0x200001ce = 0;
    *(uint8_t*)0x200001cf = 0;
    *(uint64_t*)0x200001d0 = htobe64(0);
    *(uint64_t*)0x200001d8 = htobe64(1);
    *(uint8_t*)0x200001e0 = -1;
    *(uint8_t*)0x200001e1 = 1;
    *(uint8_t*)0x200001e2 = 0;
    *(uint8_t*)0x200001e3 = 0;
    *(uint8_t*)0x200001e4 = 0;
    *(uint8_t*)0x200001e5 = 0;
    *(uint8_t*)0x200001e6 = 0;
    *(uint8_t*)0x200001e7 = 0;
    *(uint8_t*)0x200001e8 = 0;
    *(uint8_t*)0x200001e9 = 0;
    *(uint8_t*)0x200001ea = 0;
    *(uint8_t*)0x200001eb = 0;
    *(uint8_t*)0x200001ec = 0;
    *(uint8_t*)0x200001ed = 0;
    *(uint8_t*)0x200001ee = 0;
    *(uint8_t*)0x200001ef = 1;
    *(uint32_t*)0x200001f0 = 0;
    *(uint16_t*)0x200001f4 = 0xfffa;
    *(uint16_t*)0x200001f6 = 0;
    *(uint32_t*)0x200001f8 = 0;
    *(uint64_t*)0x20000200 = 0;
    *(uint32_t*)0x20000208 = 0x81000100;
    *(uint32_t*)0x2000020c = 0;
    syscall(__NR_ioctl, r[0], 0x890c, 0x200001c0);
  }
  
  int main()
  {
    syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0);
    int pid = do_sandbox_none();
    int status = 0;
    while (waitpid(pid, &status, __WALL) != pid) {
    }
    return 0;
  }
  