// https://syzkaller.appspot.com/bug?id=dbcacdc4e8b5294d8c74f43e18a753ded88ed3b6
// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE

#include <endian.h>
#include <fcntl.h>
#include <sched.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 <unistd.h>

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 long syz_open_procfs(volatile long a0, volatile 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;
}

#define USLEEP_FORKED_CHILD (3 * 50 * 1000)

static long handle_clone_ret(long ret)
{
  if (ret != 0) {
    return ret;
  }
  usleep(USLEEP_FORKED_CHILD);
  syscall(__NR_exit, 0);
  while (1) {
  }
}

static long syz_clone(volatile long flags, volatile long stack,
                      volatile long stack_len, volatile long ptid,
                      volatile long ctid, volatile long tls)
{
  long sp = (stack + stack_len) & ~15;
  long ret = (long)syscall(__NR_clone, flags & ~CLONE_VM, sp, ptid, ctid, tls);
  return handle_clone_ret(ret);
}

uint64_t r[2] = {0xffffffffffffffff, 0x0};

int main(void)
{
  syscall(__NR_mmap, /*addr=*/0x1ffff000ul, /*len=*/0x1000ul, /*prot=*/0ul,
          /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);
  syscall(__NR_mmap, /*addr=*/0x20000000ul, /*len=*/0x1000000ul, /*prot=*/7ul,
          /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);
  syscall(__NR_mmap, /*addr=*/0x21000000ul, /*len=*/0x1000ul, /*prot=*/0ul,
          /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);
  use_temporary_dir();
  intptr_t res = 0;
  memcpy((void*)0x20000100, "task\000", 5);
  res = -1;
  res = syz_open_procfs(/*pid=*/0, /*file=*/0x20000100);
  if (res != -1)
    r[0] = res;
  syscall(__NR_fchdir, /*fd=*/r[0]);
  memcpy((void*)0x20000080, ".\000", 2);
  memcpy((void*)0x200000c0, "proc\000", 5);
  syscall(__NR_mount, /*src=*/0x20000100ul, /*dst=*/0x20000080ul,
          /*type=*/0x200000c0ul, /*flags=*/0ul, /*data=*/0ul);
  res = -1;
  res = syz_clone(/*flags=*/0, /*stack=*/0, /*stack_len=*/0, /*parentid=*/0,
                  /*childtid=*/0, /*tls=*/0);
  if (res != -1)
    r[1] = res;
  syscall(__NR_tkill, /*tid=*/r[1], /*sig=*/0x38);
  syz_open_procfs(/*pid=*/r[1], /*file=*/0);
  return 0;
}