// divide error in cdc_ncm_update_rxtx_max
// https://syzkaller.appspot.com/bug?id=31f018750d6d1aa388e8ed8ad6c5e0f8653c0df8
// status:open
// 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 <sched.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stddef.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/wait.h>
#include <unistd.h>

#include <linux/capability.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/usb/ch9.h>
#include <linux/veth.h>

unsigned long long procid;

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

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 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_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 USB_DEBUG 0

#define USB_MAX_IFACE_NUM 4
#define USB_MAX_EP_NUM 32

struct usb_iface_index {
  struct usb_interface_descriptor* iface;
  struct usb_endpoint_descriptor* eps[USB_MAX_EP_NUM];
  unsigned eps_num;
};

struct usb_device_index {
  struct usb_device_descriptor* dev;
  struct usb_config_descriptor* config;
  unsigned config_length;
  struct usb_iface_index ifaces[USB_MAX_IFACE_NUM];
  unsigned ifaces_num;
};

static bool parse_usb_descriptor(char* buffer, size_t length,
                                 struct usb_device_index* index)
{
  if (length < sizeof(*index->dev) + sizeof(*index->config))
    return false;
  memset(index, 0, sizeof(*index));
  index->dev = (struct usb_device_descriptor*)buffer;
  index->config = (struct usb_config_descriptor*)(buffer + sizeof(*index->dev));
  index->config_length = length - sizeof(*index->dev);
  size_t offset = 0;
  while (true) {
    if (offset + 1 >= length)
      break;
    uint8_t desc_length = buffer[offset];
    uint8_t desc_type = buffer[offset + 1];
    if (desc_length <= 2)
      break;
    if (offset + desc_length > length)
      break;
    if (desc_type == USB_DT_INTERFACE &&
        index->ifaces_num < USB_MAX_IFACE_NUM) {
      struct usb_interface_descriptor* iface =
          (struct usb_interface_descriptor*)(buffer + offset);
      index->ifaces[index->ifaces_num++].iface = iface;
    }
    if (desc_type == USB_DT_ENDPOINT && index->ifaces_num > 0) {
      struct usb_iface_index* iface = &index->ifaces[index->ifaces_num - 1];
      if (iface->eps_num < USB_MAX_EP_NUM)
        iface->eps[iface->eps_num++] =
            (struct usb_endpoint_descriptor*)(buffer + offset);
    }
    offset += desc_length;
  }
  return true;
}

enum usb_fuzzer_event_type {
  USB_FUZZER_EVENT_INVALID,
  USB_FUZZER_EVENT_CONNECT,
  USB_FUZZER_EVENT_DISCONNECT,
  USB_FUZZER_EVENT_SUSPEND,
  USB_FUZZER_EVENT_RESUME,
  USB_FUZZER_EVENT_CONTROL,
};

struct usb_fuzzer_event {
  uint32_t type;
  uint32_t length;
  char data[0];
};

struct usb_fuzzer_init {
  uint64_t speed;
  const char* driver_name;
  const char* device_name;
};

struct usb_fuzzer_ep_io {
  uint16_t ep;
  uint16_t flags;
  uint32_t length;
  char data[0];
};

#define USB_FUZZER_IOCTL_INIT _IOW('U', 0, struct usb_fuzzer_init)
#define USB_FUZZER_IOCTL_RUN _IO('U', 1)
#define USB_FUZZER_IOCTL_EVENT_FETCH _IOR('U', 2, struct usb_fuzzer_event)
#define USB_FUZZER_IOCTL_EP0_WRITE _IOW('U', 3, struct usb_fuzzer_ep_io)
#define USB_FUZZER_IOCTL_EP0_READ _IOWR('U', 4, struct usb_fuzzer_ep_io)
#define USB_FUZZER_IOCTL_EP_ENABLE _IOW('U', 5, struct usb_endpoint_descriptor)
#define USB_FUZZER_IOCTL_EP_WRITE _IOW('U', 7, struct usb_fuzzer_ep_io)
#define USB_FUZZER_IOCTL_EP_READ _IOWR('U', 8, struct usb_fuzzer_ep_io)
#define USB_FUZZER_IOCTL_CONFIGURE _IO('U', 9)
#define USB_FUZZER_IOCTL_VBUS_DRAW _IOW('U', 10, uint32_t)

int usb_fuzzer_open()
{
  return open("/sys/kernel/debug/usb-fuzzer", O_RDWR);
}

int usb_fuzzer_init(int fd, uint32_t speed, const char* driver,
                    const char* device)
{
  struct usb_fuzzer_init arg;
  arg.speed = speed;
  arg.driver_name = driver;
  arg.device_name = device;
  return ioctl(fd, USB_FUZZER_IOCTL_INIT, &arg);
}

int usb_fuzzer_run(int fd)
{
  return ioctl(fd, USB_FUZZER_IOCTL_RUN, 0);
}

int usb_fuzzer_event_fetch(int fd, struct usb_fuzzer_event* event)
{
  return ioctl(fd, USB_FUZZER_IOCTL_EVENT_FETCH, event);
}

int usb_fuzzer_ep0_write(int fd, struct usb_fuzzer_ep_io* io)
{
  return ioctl(fd, USB_FUZZER_IOCTL_EP0_WRITE, io);
}

int usb_fuzzer_ep0_read(int fd, struct usb_fuzzer_ep_io* io)
{
  return ioctl(fd, USB_FUZZER_IOCTL_EP0_READ, io);
}

int usb_fuzzer_ep_write(int fd, struct usb_fuzzer_ep_io* io)
{
  return ioctl(fd, USB_FUZZER_IOCTL_EP_WRITE, io);
}

int usb_fuzzer_ep_read(int fd, struct usb_fuzzer_ep_io* io)
{
  return ioctl(fd, USB_FUZZER_IOCTL_EP_READ, io);
}

int usb_fuzzer_ep_enable(int fd, struct usb_endpoint_descriptor* desc)
{
  return ioctl(fd, USB_FUZZER_IOCTL_EP_ENABLE, desc);
}

int usb_fuzzer_configure(int fd)
{
  return ioctl(fd, USB_FUZZER_IOCTL_CONFIGURE, 0);
}

int usb_fuzzer_vbus_draw(int fd, uint32_t power)
{
  return ioctl(fd, USB_FUZZER_IOCTL_VBUS_DRAW, power);
}

#define USB_MAX_PACKET_SIZE 1024

struct usb_fuzzer_control_event {
  struct usb_fuzzer_event inner;
  struct usb_ctrlrequest ctrl;
  char data[USB_MAX_PACKET_SIZE];
};

struct usb_fuzzer_ep_io_data {
  struct usb_fuzzer_ep_io inner;
  char data[USB_MAX_PACKET_SIZE];
};

struct vusb_connect_string_descriptor {
  uint32_t len;
  char* str;
} __attribute__((packed));

struct vusb_connect_descriptors {
  uint32_t qual_len;
  char* qual;
  uint32_t bos_len;
  char* bos;
  uint32_t strs_len;
  struct vusb_connect_string_descriptor strs[0];
} __attribute__((packed));

static const char default_string[] = {8, USB_DT_STRING, 's', 0, 'y', 0, 'z', 0};

static const char default_lang_id[] = {4, USB_DT_STRING, 0x09, 0x04};

static bool lookup_connect_response(struct vusb_connect_descriptors* descs,
                                    struct usb_device_index* index,
                                    struct usb_ctrlrequest* ctrl,
                                    char** response_data,
                                    uint32_t* response_length)
{
  uint8_t str_idx;
  switch (ctrl->bRequestType & USB_TYPE_MASK) {
  case USB_TYPE_STANDARD:
    switch (ctrl->bRequest) {
    case USB_REQ_GET_DESCRIPTOR:
      switch (ctrl->wValue >> 8) {
      case USB_DT_DEVICE:
        *response_data = (char*)index->dev;
        *response_length = sizeof(*index->dev);
        return true;
      case USB_DT_CONFIG:
        *response_data = (char*)index->config;
        *response_length = index->config_length;
        return true;
      case USB_DT_STRING:
        str_idx = (uint8_t)ctrl->wValue;
        if (descs && str_idx < descs->strs_len) {
          *response_data = descs->strs[str_idx].str;
          *response_length = descs->strs[str_idx].len;
          return true;
        }
        if (str_idx == 0) {
          *response_data = (char*)&default_lang_id[0];
          *response_length = default_lang_id[0];
          return true;
        }
        *response_data = (char*)&default_string[0];
        *response_length = default_string[0];
        return true;
      case USB_DT_BOS:
        *response_data = descs->bos;
        *response_length = descs->bos_len;
        return true;
      case USB_DT_DEVICE_QUALIFIER:
        *response_data = descs->qual;
        *response_length = descs->qual_len;
        return true;
      default:
        exit(1);
        return false;
      }
      break;
    default:
      exit(1);
      return false;
    }
    break;
  default:
    exit(1);
    return false;
  }
  return false;
}

static volatile long syz_usb_connect(volatile long a0, volatile long a1,
                                     volatile long a2, volatile long a3)
{
  uint64_t speed = a0;
  uint64_t dev_len = a1;
  char* dev = (char*)a2;
  struct vusb_connect_descriptors* descs = (struct vusb_connect_descriptors*)a3;
  if (!dev) {
    return -1;
  }
  struct usb_device_index index;
  memset(&index, 0, sizeof(index));
  int rv = 0;
  rv = parse_usb_descriptor(dev, dev_len, &index);
  if (!rv) {
    return rv;
  }
  int fd = usb_fuzzer_open();
  if (fd < 0) {
    return fd;
  }
  char device[32];
  sprintf(&device[0], "dummy_udc.%llu", procid);
  rv = usb_fuzzer_init(fd, speed, "dummy_udc", &device[0]);
  if (rv < 0) {
    return rv;
  }
  rv = usb_fuzzer_run(fd);
  if (rv < 0) {
    return rv;
  }
  bool done = false;
  while (!done) {
    struct usb_fuzzer_control_event event;
    event.inner.type = 0;
    event.inner.length = sizeof(event.ctrl);
    rv = usb_fuzzer_event_fetch(fd, (struct usb_fuzzer_event*)&event);
    if (rv < 0) {
      return rv;
    }
    if (event.inner.type != USB_FUZZER_EVENT_CONTROL)
      continue;
    bool response_found = false;
    char* response_data = NULL;
    uint32_t response_length = 0;
    if (event.ctrl.bRequestType & USB_DIR_IN) {
      response_found = lookup_connect_response(
          descs, &index, &event.ctrl, &response_data, &response_length);
      if (!response_found) {
        return -1;
      }
    } else {
      if ((event.ctrl.bRequestType & USB_TYPE_MASK) != USB_TYPE_STANDARD ||
          event.ctrl.bRequest != USB_REQ_SET_CONFIGURATION) {
        exit(1);
        return -1;
      }
      done = true;
    }
    if (done) {
      rv = usb_fuzzer_vbus_draw(fd, index.config->bMaxPower);
      if (rv < 0) {
        return rv;
      }
      rv = usb_fuzzer_configure(fd);
      if (rv < 0) {
        return rv;
      }
      unsigned ep;
      for (ep = 0; ep < index.ifaces[0].eps_num; ep++) {
        rv = usb_fuzzer_ep_enable(fd, index.ifaces[0].eps[ep]);
        if (rv < 0) {
        } else {
        }
      }
    }
    struct usb_fuzzer_ep_io_data response;
    response.inner.ep = 0;
    response.inner.flags = 0;
    if (response_length > sizeof(response.data))
      response_length = 0;
    if (event.ctrl.wLength < response_length)
      response_length = event.ctrl.wLength;
    response.inner.length = response_length;
    if (response_data)
      memcpy(&response.data[0], response_data, response_length);
    else
      memset(&response.data[0], 0, response_length);
    if (event.ctrl.bRequestType & USB_DIR_IN) {
      rv = usb_fuzzer_ep0_write(fd, (struct usb_fuzzer_ep_io*)&response);
    } else {
      rv = usb_fuzzer_ep0_read(fd, (struct usb_fuzzer_ep_io*)&response);
    }
    if (rv < 0) {
      return rv;
    }
  }
  sleep_ms(200);
  return fd;
}

struct vusb_descriptor {
  uint8_t req_type;
  uint8_t desc_type;
  uint32_t len;
  char data[0];
} __attribute__((packed));

struct vusb_descriptors {
  uint32_t len;
  struct vusb_descriptor* generic;
  struct vusb_descriptor* descs[0];
} __attribute__((packed));

struct vusb_response {
  uint8_t type;
  uint8_t req;
  uint32_t len;
  char data[0];
} __attribute__((packed));

struct vusb_responses {
  uint32_t len;
  struct vusb_response* generic;
  struct vusb_response* resps[0];
} __attribute__((packed));

static bool lookup_control_response(struct vusb_descriptors* descs,
                                    struct vusb_responses* resps,
                                    struct usb_ctrlrequest* ctrl,
                                    char** response_data,
                                    uint32_t* response_length)
{
  int descs_num = 0;
  int resps_num = 0;
  if (descs)
    descs_num = (descs->len - offsetof(struct vusb_descriptors, descs)) /
                sizeof(descs->descs[0]);
  if (resps)
    resps_num = (resps->len - offsetof(struct vusb_responses, resps)) /
                sizeof(resps->resps[0]);
  uint8_t req = ctrl->bRequest;
  uint8_t req_type = ctrl->bRequestType & USB_TYPE_MASK;
  uint8_t desc_type = ctrl->wValue >> 8;
  if (req == USB_REQ_GET_DESCRIPTOR) {
    int i;
    for (i = 0; i < descs_num; i++) {
      struct vusb_descriptor* desc = descs->descs[i];
      if (!desc)
        continue;
      if (desc->req_type == req_type && desc->desc_type == desc_type) {
        *response_length = desc->len;
        if (*response_length != 0)
          *response_data = &desc->data[0];
        else
          *response_data = NULL;
        return true;
      }
    }
    if (descs && descs->generic) {
      *response_data = &descs->generic->data[0];
      *response_length = descs->generic->len;
      return true;
    }
  } else {
    int i;
    for (i = 0; i < resps_num; i++) {
      struct vusb_response* resp = resps->resps[i];
      if (!resp)
        continue;
      if (resp->type == req_type && resp->req == req) {
        *response_length = resp->len;
        if (*response_length != 0)
          *response_data = &resp->data[0];
        else
          *response_data = NULL;
        return true;
      }
    }
    if (resps && resps->generic) {
      *response_data = &resps->generic->data[0];
      *response_length = resps->generic->len;
      return true;
    }
  }
  return false;
}

static volatile long syz_usb_control_io(volatile long a0, volatile long a1,
                                        volatile long a2)
{
  int fd = a0;
  struct vusb_descriptors* descs = (struct vusb_descriptors*)a1;
  struct vusb_responses* resps = (struct vusb_responses*)a2;
  struct usb_fuzzer_control_event event;
  event.inner.type = 0;
  event.inner.length = USB_MAX_PACKET_SIZE;
  int rv = usb_fuzzer_event_fetch(fd, (struct usb_fuzzer_event*)&event);
  if (rv < 0) {
    return rv;
  }
  if (event.inner.type != USB_FUZZER_EVENT_CONTROL) {
    return -1;
  }
  bool response_found = false;
  char* response_data = NULL;
  uint32_t response_length = 0;
  if (event.ctrl.bRequestType & USB_DIR_IN) {
    response_found = lookup_control_response(descs, resps, &event.ctrl,
                                             &response_data, &response_length);
    if (!response_found) {
      return -1;
    }
  } else {
    response_length = event.ctrl.wLength;
  }
  struct usb_fuzzer_ep_io_data response;
  response.inner.ep = 0;
  response.inner.flags = 0;
  if (response_length > sizeof(response.data))
    response_length = 0;
  if (event.ctrl.wLength < response_length)
    response_length = event.ctrl.wLength;
  response.inner.length = response_length;
  if (response_data)
    memcpy(&response.data[0], response_data, response_length);
  else
    memset(&response.data[0], 0, response_length);
  if (event.ctrl.bRequestType & USB_DIR_IN) {
    rv = usb_fuzzer_ep0_write(fd, (struct usb_fuzzer_ep_io*)&response);
  } else {
    rv = usb_fuzzer_ep0_read(fd, (struct usb_fuzzer_ep_io*)&response);
  }
  if (rv < 0) {
    return rv;
  }
  sleep_ms(200);
  return 0;
}

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 void drop_caps(void)
{
  struct __user_cap_header_struct cap_hdr = {};
  struct __user_cap_data_struct cap_data[2] = {};
  cap_hdr.version = _LINUX_CAPABILITY_VERSION_3;
  cap_hdr.pid = getpid();
  if (syscall(SYS_capget, &cap_hdr, &cap_data))
    exit(1);
  const int drop = (1 << CAP_SYS_PTRACE) | (1 << CAP_SYS_NICE);
  cap_data[0].effective &= ~drop;
  cap_data[0].permitted &= ~drop;
  cap_data[0].inheritable &= ~drop;
  if (syscall(SYS_capset, &cap_hdr, &cap_data))
    exit(1);
}

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();
  drop_caps();
  if (unshare(CLONE_NEWNET)) {
  }
  initialize_tun();
  loop();
  exit(1);
}

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

uint64_t r[1] = {0xffffffffffffffff};

void loop(void)
{
  intptr_t res = 0;
  *(uint8_t*)0x20000000 = 0x12;
  *(uint8_t*)0x20000001 = 1;
  *(uint16_t*)0x20000002 = 0;
  *(uint8_t*)0x20000004 = 2;
  *(uint8_t*)0x20000005 = 0;
  *(uint8_t*)0x20000006 = 0;
  *(uint8_t*)0x20000007 = 0x40;
  *(uint16_t*)0x20000008 = 0x525;
  *(uint16_t*)0x2000000a = 0xa4a1;
  *(uint16_t*)0x2000000c = 0x40;
  *(uint8_t*)0x2000000e = 1;
  *(uint8_t*)0x2000000f = 2;
  *(uint8_t*)0x20000010 = 3;
  *(uint8_t*)0x20000011 = 1;
  *(uint8_t*)0x20000012 = 9;
  *(uint8_t*)0x20000013 = 2;
  *(uint16_t*)0x20000014 = 0x5c;
  *(uint8_t*)0x20000016 = 2;
  *(uint8_t*)0x20000017 = 1;
  *(uint8_t*)0x20000018 = 0;
  *(uint8_t*)0x20000019 = 0;
  *(uint8_t*)0x2000001a = 0;
  *(uint8_t*)0x2000001b = 9;
  *(uint8_t*)0x2000001c = 4;
  *(uint8_t*)0x2000001d = 0;
  *(uint8_t*)0x2000001e = 0;
  *(uint8_t*)0x2000001f = 1;
  *(uint8_t*)0x20000020 = 2;
  *(uint8_t*)0x20000021 = 0xd;
  *(uint8_t*)0x20000022 = 0;
  *(uint8_t*)0x20000023 = 0;
  *(uint8_t*)0x20000024 = 5;
  *(uint8_t*)0x20000025 = 0x24;
  *(uint8_t*)0x20000026 = 6;
  *(uint8_t*)0x20000027 = 0;
  *(uint8_t*)0x20000028 = 1;
  *(uint8_t*)0x20000029 = 5;
  *(uint8_t*)0x2000002a = 0x24;
  *(uint8_t*)0x2000002b = 0;
  *(uint16_t*)0x2000002c = 0;
  *(uint8_t*)0x2000002e = 0xd;
  *(uint8_t*)0x2000002f = 0x24;
  *(uint8_t*)0x20000030 = 0xf;
  *(uint8_t*)0x20000031 = 1;
  *(uint32_t*)0x20000032 = 0;
  *(uint16_t*)0x20000036 = 0;
  *(uint16_t*)0x20000038 = 0;
  *(uint8_t*)0x2000003a = 0;
  *(uint8_t*)0x2000003b = 6;
  *(uint8_t*)0x2000003c = 0x24;
  *(uint8_t*)0x2000003d = 0x1a;
  *(uint16_t*)0x2000003e = 0;
  *(uint8_t*)0x20000040 = 0;
  *(uint8_t*)0x20000041 = 9;
  *(uint8_t*)0x20000042 = 5;
  *(uint8_t*)0x20000043 = 0x81;
  *(uint8_t*)0x20000044 = 3;
  *(uint16_t*)0x20000045 = 0;
  *(uint8_t*)0x20000047 = 0;
  *(uint8_t*)0x20000048 = 0;
  *(uint8_t*)0x20000049 = 0;
  *(uint8_t*)0x2000004a = 9;
  *(uint8_t*)0x2000004b = 4;
  *(uint8_t*)0x2000004c = 1;
  *(uint8_t*)0x2000004d = 0;
  *(uint8_t*)0x2000004e = 0;
  *(uint8_t*)0x2000004f = 2;
  *(uint8_t*)0x20000050 = 0xd;
  *(uint8_t*)0x20000051 = 0;
  *(uint8_t*)0x20000052 = 0;
  *(uint8_t*)0x20000053 = 9;
  *(uint8_t*)0x20000054 = 4;
  *(uint8_t*)0x20000055 = 1;
  *(uint8_t*)0x20000056 = 1;
  *(uint8_t*)0x20000057 = 2;
  *(uint8_t*)0x20000058 = 2;
  *(uint8_t*)0x20000059 = 0xd;
  *(uint8_t*)0x2000005a = 0;
  *(uint8_t*)0x2000005b = 0;
  *(uint8_t*)0x2000005c = 9;
  *(uint8_t*)0x2000005d = 5;
  *(uint8_t*)0x2000005e = 0x82;
  *(uint8_t*)0x2000005f = 2;
  *(uint16_t*)0x20000060 = 0;
  *(uint8_t*)0x20000062 = 0;
  *(uint8_t*)0x20000063 = 0;
  *(uint8_t*)0x20000064 = 0;
  *(uint8_t*)0x20000065 = 9;
  *(uint8_t*)0x20000066 = 5;
  *(uint8_t*)0x20000067 = 3;
  *(uint8_t*)0x20000068 = 2;
  *(uint16_t*)0x20000069 = 0;
  *(uint8_t*)0x2000006b = 0;
  *(uint8_t*)0x2000006c = 0;
  *(uint8_t*)0x2000006d = 0;
  res = syz_usb_connect(0, 0x6e, 0x20000000, 0);
  if (res != -1)
    r[0] = res;
  syz_usb_control_io(r[0], 0, 0);
  syz_usb_control_io(r[0], 0, 0);
  *(uint32_t*)0x20000900 = 0x44;
  *(uint64_t*)0x20000904 = 0;
  *(uint64_t*)0x2000090c = 0;
  *(uint64_t*)0x20000914 = 0;
  *(uint64_t*)0x2000091c = 0x200007c0;
  *(uint8_t*)0x200007c0 = 0x20;
  *(uint8_t*)0x200007c1 = 0x80;
  *(uint32_t*)0x200007c2 = 0x1c;
  *(uint16_t*)0x200007c6 = 0x3b;
  *(uint16_t*)0x200007c8 = 1;
  *(uint32_t*)0x200007ca = 0;
  *(uint16_t*)0x200007ce = 0xcca;
  *(uint16_t*)0x200007d0 = 1;
  *(uint16_t*)0x200007d2 = 7;
  *(uint16_t*)0x200007d4 = 6;
  *(uint32_t*)0x200007d6 = 0x7fff;
  *(uint16_t*)0x200007da = 8;
  *(uint16_t*)0x200007dc = 0x80;
  *(uint16_t*)0x200007de = 0xa10;
  *(uint16_t*)0x200007e0 = 0xfffc;
  *(uint64_t*)0x20000924 = 0;
  *(uint64_t*)0x2000092c = 0;
  *(uint64_t*)0x20000934 = 0;
  *(uint64_t*)0x2000093c = 0;
  syz_usb_control_io(r[0], 0, 0x20000900);
  syz_usb_control_io(r[0], 0, 0);
  *(uint32_t*)0x200001c0 = 0x14;
  *(uint64_t*)0x200001c4 = 0;
  *(uint64_t*)0x200001cc = 0x20000180;
  *(uint8_t*)0x20000180 = 0;
  *(uint8_t*)0x20000181 = 3;
  *(uint32_t*)0x20000182 = 0x1a;
  *(uint8_t*)0x20000186 = 0x1a;
  *(uint8_t*)0x20000187 = 3;
  *(uint64_t*)0x20000188 = htobe64(0x3400320034003200);
  *(uint64_t*)0x20000190 = htobe64(0x3400320034003200);
  *(uint64_t*)0x20000198 = htobe64(0x3400320034003200);
  syz_usb_control_io(r[0], 0x200001c0, 0);
  close_fds();
}
int main(void)
{
  syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0);
  do_sandbox_none();
  return 0;
}