text: // WARNING in inc_nlink (2)
  // https://syzkaller.appspot.com/bug?id=3fbbd90094e3d827144b
  // status:0
  // autogenerated by syzkaller (https://github.com/google/syzkaller)
  
  #define _GNU_SOURCE
  
  #include <endian.h>
  #include <errno.h>
  #include <fcntl.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/stat.h>
  #include <sys/syscall.h>
  #include <sys/types.h>
  #include <unistd.h>
  
  #include <linux/loop.h>
  
  static unsigned long long procid;
  
  struct fs_image_segment {
    void* data;
    uintptr_t size;
    uintptr_t offset;
  };
  
  #define IMAGE_MAX_SEGMENTS 4096
  #define IMAGE_MAX_SIZE (129 << 20)
  
  #define sys_memfd_create 319
  
  static unsigned long fs_image_segment_check(unsigned long size,
                                              unsigned long nsegs,
                                              struct fs_image_segment* segs)
  {
    if (nsegs > IMAGE_MAX_SEGMENTS)
      nsegs = IMAGE_MAX_SEGMENTS;
    for (size_t i = 0; i < nsegs; i++) {
      if (segs[i].size > IMAGE_MAX_SIZE)
        segs[i].size = IMAGE_MAX_SIZE;
      segs[i].offset %= IMAGE_MAX_SIZE;
      if (segs[i].offset > IMAGE_MAX_SIZE - segs[i].size)
        segs[i].offset = IMAGE_MAX_SIZE - segs[i].size;
      if (size < segs[i].offset + segs[i].offset)
        size = segs[i].offset + segs[i].offset;
    }
    if (size > IMAGE_MAX_SIZE)
      size = IMAGE_MAX_SIZE;
    return size;
  }
  static int setup_loop_device(long unsigned size, long unsigned nsegs,
                               struct fs_image_segment* segs,
                               const char* loopname, int* memfd_p, int* loopfd_p)
  {
    int err = 0, loopfd = -1;
    size = fs_image_segment_check(size, nsegs, segs);
    int memfd = syscall(sys_memfd_create, "syzkaller", 0);
    if (memfd == -1) {
      err = errno;
      goto error;
    }
    if (ftruncate(memfd, size)) {
      err = errno;
      goto error_close_memfd;
    }
    for (size_t i = 0; i < nsegs; i++) {
      if (pwrite(memfd, segs[i].data, segs[i].size, segs[i].offset) < 0) {
      }
    }
    loopfd = open(loopname, O_RDWR);
    if (loopfd == -1) {
      err = errno;
      goto error_close_memfd;
    }
    if (ioctl(loopfd, LOOP_SET_FD, memfd)) {
      if (errno != EBUSY) {
        err = errno;
        goto error_close_loop;
      }
      ioctl(loopfd, LOOP_CLR_FD, 0);
      usleep(1000);
      if (ioctl(loopfd, LOOP_SET_FD, memfd)) {
        err = errno;
        goto error_close_loop;
      }
    }
    *memfd_p = memfd;
    *loopfd_p = loopfd;
    return 0;
  
  error_close_loop:
    close(loopfd);
  error_close_memfd:
    close(memfd);
  error:
    errno = err;
    return -1;
  }
  
  static long syz_mount_image(volatile long fsarg, volatile long dir,
                              volatile unsigned long size,
                              volatile unsigned long nsegs,
                              volatile long segments, volatile long flags,
                              volatile long optsarg)
  {
    struct fs_image_segment* segs = (struct fs_image_segment*)segments;
    int res = -1, err = 0, loopfd = -1, memfd = -1, need_loop_device = !!segs;
    char* mount_opts = (char*)optsarg;
    char* target = (char*)dir;
    char* fs = (char*)fsarg;
    char* source = NULL;
    char loopname[64];
    if (need_loop_device) {
      memset(loopname, 0, sizeof(loopname));
      snprintf(loopname, sizeof(loopname), "/dev/loop%llu", procid);
      if (setup_loop_device(size, nsegs, segs, loopname, &memfd, &loopfd) == -1)
        return -1;
      source = loopname;
    }
    mkdir(target, 0777);
    char opts[256];
    memset(opts, 0, sizeof(opts));
    if (strlen(mount_opts) > (sizeof(opts) - 32)) {
    }
    strncpy(opts, mount_opts, sizeof(opts) - 32);
    if (strcmp(fs, "iso9660") == 0) {
      flags |= MS_RDONLY;
    } else if (strncmp(fs, "ext", 3) == 0) {
      if (strstr(opts, "errors=panic") || strstr(opts, "errors=remount-ro") == 0)
        strcat(opts, ",errors=continue");
    } else if (strcmp(fs, "xfs") == 0) {
      strcat(opts, ",nouuid");
    }
    res = mount(source, target, fs, flags, opts);
    if (res == -1) {
      err = errno;
      goto error_clear_loop;
    }
    res = open(target, O_RDONLY | O_DIRECTORY);
    if (res == -1) {
      err = errno;
    }
  
  error_clear_loop:
    if (need_loop_device) {
      ioctl(loopfd, LOOP_CLR_FD, 0);
      close(loopfd);
      close(memfd);
    }
    errno = err;
    return res;
  }
  
  int main(void)
  {
    syscall(__NR_mmap, 0x1ffff000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
    syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul);
    syscall(__NR_mmap, 0x21000000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
  
    memcpy((void*)0x20000000, "v7\000", 3);
    memcpy((void*)0x20000040, "./file0\000", 8);
    *(uint64_t*)0x20000540 = 0x20000100;
    memcpy((void*)0x20000100, "\xb8\x29\x53\xd2\xf7\x85\xce\x8d\x3d\x10\x94\x13"
                              "\x13\xc3\xaf\xae\x88\xbb\xf7\x63\xf7\x2b\x62\xab"
                              "\xd0\xa1\xce\xdc\x8f\x8c\x3c\xff\x20\xef\xb5\x79"
                              "\x88\x7a\x1b\x8b\x17\x39\x6d\xbf\x5d\x02\xbc\xfe"
                              "\x7a\x54\x4c\x29\xbb\xe6\xfb\x84\x61\xe9\xb4\x93"
                              "\x5c\xe2\x54\x7b\x41\x00\x00\x02\x73\xee\xa3\xe0",
           72);
    *(uint64_t*)0x20000548 = 0x48;
    *(uint64_t*)0x20000550 = 0x401;
    syz_mount_image(0x20000000, 0x20000040, 0, 1, 0x20000540, 0, 0x20000c00);
    memcpy((void*)0x20000080, "./file0/file0\000", 14);
    syscall(__NR_mkdir, 0x20000080ul, 0x23ul);
    return 0;
  }
  