// https://syzkaller.appspot.com/bug?id=597b2fc85015dc9145b56a848e646e78217acba9
// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE

#include <endian.h>
#include <fcntl.h>
#include <pthread.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>

#include <linux/futex.h>

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

static uint64_t current_time_ms()
{
  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 thread_start(void* (*fn)(void*), void* arg)
{
  pthread_t th;
  pthread_attr_t attr;
  pthread_attr_init(&attr);
  pthread_attr_setstacksize(&attr, 128 << 10);
  if (pthread_create(&th, &attr, fn, arg))
    exit(1);
  pthread_attr_destroy(&attr);
}

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);
}

static void event_wait(event_t* ev)
{
  while (!__atomic_load_n(&ev->state, __ATOMIC_ACQUIRE))
    syscall(SYS_futex, &ev->state, FUTEX_WAIT, 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, 0, &ts);
    if (__atomic_load_n(&ev->state, __ATOMIC_RELAXED))
      return 1;
    now = current_time_ms();
    if (now - start > timeout)
      return 0;
  }
}

static long syz_open_procfs(long a0, long a1)
{
  char buf[128];
  memset(buf, 0, sizeof(buf));
  if (a0 == 0) {
    snprintf(buf, sizeof(buf), "/proc/self/%s", (char*)a1);
  } else if (a0 == -1) {
    snprintf(buf, sizeof(buf), "/proc/thread-self/%s", (char*)a1);
  } else {
    snprintf(buf, sizeof(buf), "/proc/self/task/%d/%s", (int)a0, (char*)a1);
  }
  int fd = open(buf, O_RDWR);
  if (fd == -1)
    fd = open(buf, O_RDONLY);
  return fd;
}

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()
{
  int i, call, thread;
  int collide = 0;
again:
  for (call = 0; call < 4; call++) {
    for (thread = 0; thread < 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);
  if (!collide) {
    collide = 1;
    goto again;
  }
}

uint64_t r[1] = {0xffffffffffffffff};

void execute_call(int call)
{
  long res;
  switch (call) {
  case 0:
    memcpy((void*)0x20000180,
           "\x74\x61\x73\x6b\x00\x7b\xc6\x9d\x49\x4c\x9f\x65\xf3\xb0\x84\xe2"
           "\x02\xa4\x7b\x84\x57\x32\x93\x05\x45\xea\xc9\x0c\x90\x1a\x30\x94"
           "\xb8\xfe\x22\xde\x36\xf0\xd8\x5a\xe8\xed\x6c\xf3\x36\x57\xb8\x79"
           "\x39\x60\x0f\x31\x6d\x92\x07\xfe\xf2\xaf\xfc\xa8\x74\xab\x29\x70"
           "\x00\x5b\x20\x1a\xc6\x57\x86\x26\x84\xe0\x17\xca\x2d\x02\xb4\xe7"
           "\xee\xcb\x5d\xbb\xe2\x84\x25\xdf\xd4\xf3\xe8\xd1\x6a\xd6\x2c\x9f"
           "\xaa\x66\x7d\x1b\xe6\xf4\x55\x0d\x41\x86\x1a\x4e\xe7\x65\xa0\x04"
           "\xd1\xf5\x6b\xd1\x69\x29\x12\xca\x86\x1e\xe3\x15\xa5\x7e\xc3\x23"
           "\x52\x99\xfc\xdf\x53\x2f\xce\x59\x74\x02\x29\x6c\x9c\xcd\x54\xbb"
           "\x43\x65\x3c\xef\x30\xe1\xa1\x18\x78\x82\x56\xf8\xf4\xec\x35\x67"
           "\xe8\x82\x1c\x44\xa7\x34\xba\xbb\xe7\x25\x0d\xa2\xcc\x5a\x87\x2b"
           "\x3b\xda\x93\xcc\xd5\x43\x42\x5d\x18\xdc\x61\x7d\x7f\x6a\xbf\xbf"
           "\xa0\xc6\x6d\xbc\xc6\x9f\x75\x38\x94\xee\x34",
           203);
    res = syz_open_procfs(0, 0x20000180);
    if (res != -1)
      r[0] = res;
    break;
  case 1:
    syscall(__NR_getdents64, r[0], 0x20001380, 0x1000);
    break;
  case 2:
    syscall(__NR_fcntl, r[0], 0x402, 0x31);
    break;
  case 3:
    syscall(__NR_exit, 0);
    break;
  }
}
int main()
{
  syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0);
  loop();
  return 0;
}