// https://syzkaller.appspot.com/bug?id=b1dafb8ee4f256d2f56693e6cd145c01c92b76cd
// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE

#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <setjmp.h>
#include <signal.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>

#ifndef __NR_memfd_create
#define __NR_memfd_create 319
#endif

static unsigned long long procid;

static __thread int clone_ongoing;
static __thread int skip_segv;
static __thread jmp_buf segv_env;

static void segv_handler(int sig, siginfo_t* info, void* ctx)
{
  if (__atomic_load_n(&clone_ongoing, __ATOMIC_RELAXED) != 0) {
    exit(sig);
  }
  uintptr_t addr = (uintptr_t)info->si_addr;
  const uintptr_t prog_start = 1 << 20;
  const uintptr_t prog_end = 100 << 20;
  int skip = __atomic_load_n(&skip_segv, __ATOMIC_RELAXED) != 0;
  int valid = addr < prog_start || addr > prog_end;
  if (skip && valid) {
    _longjmp(segv_env, 1);
  }
  exit(sig);
}

static void install_segv_handler(void)
{
  struct sigaction sa;
  memset(&sa, 0, sizeof(sa));
  sa.sa_handler = SIG_IGN;
  syscall(SYS_rt_sigaction, 0x20, &sa, NULL, 8);
  syscall(SYS_rt_sigaction, 0x21, &sa, NULL, 8);
  memset(&sa, 0, sizeof(sa));
  sa.sa_sigaction = segv_handler;
  sa.sa_flags = SA_NODEFER | SA_SIGINFO;
  sigaction(SIGSEGV, &sa, NULL);
  sigaction(SIGBUS, &sa, NULL);
}

#define NONFAILING(...)                                                        \
  ({                                                                           \
    int ok = 1;                                                                \
    __atomic_fetch_add(&skip_segv, 1, __ATOMIC_SEQ_CST);                       \
    if (_setjmp(segv_env) == 0) {                                              \
      __VA_ARGS__;                                                             \
    } else                                                                     \
      ok = 0;                                                                  \
    __atomic_fetch_sub(&skip_segv, 1, __ATOMIC_SEQ_CST);                       \
    ok;                                                                        \
  })

struct fs_image_segment {
  void* data;
  uintptr_t size;
  uintptr_t offset;
};

#define IMAGE_MAX_SEGMENTS 4096
#define IMAGE_MAX_SIZE (129 << 20)

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(__NR_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);
  install_segv_handler();
  NONFAILING(memcpy((void*)0x20000140, "./file0\000", 8));
  NONFAILING(syz_mount_image(0, 0x20000140, 0, 0, 0, 0, 0));
  NONFAILING(memcpy((void*)0x20000080, "./file0\000", 8));
  NONFAILING(memcpy((void*)0x20000040, "./file0\000", 8));
  NONFAILING(memcpy((void*)0x20000200, "incremental-fs\000", 15));
  syscall(__NR_mount, 0x20000080ul, 0x20000040ul, 0x20000200ul, 0ul, 0ul);
  {
    int i;
    for (i = 0; i < 64; i++) {
      syscall(__NR_mount, 0x20000080ul, 0x20000040ul, 0x20000200ul, 0ul, 0ul);
    }
  }
  NONFAILING(memcpy((void*)0x20000000, "./file0\000", 8));
  NONFAILING(
      memcpy((void*)0x20000100,
             "\x73\x93\x96\x03\x78\x11\x18\x2f\xd9\x78\x08\xca\x32\x94\xc2\xdf"
             "\xaf\x69\x6e\x63\x72\x65\x6d\x65\x6e\x74\x41\x6c\x2d\x66\x73\x00",
             32));
  syscall(__NR_removexattr, 0x20000000ul, 0x20000100ul);
  return 0;
}