// https://syzkaller.appspot.com/bug?id=53ccc587c0930bffa25255ab4c12c1e6ba9b380a
// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE

#include <endian.h>
#include <setjmp.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>

#ifndef __NR_epoll_create1
#define __NR_epoll_create1 20
#endif
#ifndef __NR_epoll_ctl
#define __NR_epoll_ctl 21
#endif
#ifndef __NR_epoll_pwait2
#define __NR_epoll_pwait2 441
#endif
#ifndef __NR_mmap
#define __NR_mmap 222
#endif
#ifndef __NR_mprotect
#define __NR_mprotect 226
#endif
#ifndef __NR_userfaultfd
#define __NR_userfaultfd 282
#endif

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;                                                                        \
  })

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

int main(void)
{
  syscall(__NR_mmap, /*addr=*/0x1ffff000ul, /*len=*/0x1000ul, /*prot=*/0ul,
          /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul,
          /*fd=*/(intptr_t)-1, /*offset=*/0ul);
  syscall(__NR_mmap, /*addr=*/0x20000000ul, /*len=*/0x1000000ul,
          /*prot=PROT_WRITE|PROT_READ|PROT_EXEC*/ 7ul,
          /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul,
          /*fd=*/(intptr_t)-1, /*offset=*/0ul);
  syscall(__NR_mmap, /*addr=*/0x21000000ul, /*len=*/0x1000ul, /*prot=*/0ul,
          /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul,
          /*fd=*/(intptr_t)-1, /*offset=*/0ul);
  const char* reason;
  (void)reason;
  install_segv_handler();
  intptr_t res = 0;
  if (write(1, "executing program\n", sizeof("executing program\n") - 1)) {
  }
  //  mprotect arguments: [
  //    addr: VMA[0xf000]
  //    len: len = 0xf000 (8 bytes)
  //    prot: mmap_prot = 0x1 (8 bytes)
  //  ]
  syscall(__NR_mprotect, /*addr=*/0x20000000ul, /*len=*/0xf000ul,
          /*prot=PROT_READ*/ 1ul);
  //  epoll_create1 arguments: [
  //    flags: epoll_flags = 0x0 (8 bytes)
  //  ]
  //  returns fd_epoll
  res = syscall(__NR_epoll_create1, /*flags=*/0ul);
  if (res != -1)
    r[0] = res;
  //  userfaultfd arguments: [
  //    flags: userfaultfd_flags = 0x80801 (8 bytes)
  //  ]
  //  returns fd_uffd
  res = syscall(__NR_userfaultfd,
                /*flags=UFFD_USER_MODE_ONLY|O_CLOEXEC|O_NONBLOCK*/ 0x80801ul);
  if (res != -1)
    r[1] = res;
  //  epoll_ctl$EPOLL_CTL_ADD arguments: [
  //    epfd: fd_epoll (resource)
  //    op: const = 0x1 (8 bytes)
  //    fd: fd (resource)
  //    ev: ptr[in, epoll_event] {
  //      epoll_event {
  //        ev: epoll_ev = 0xb0002016 (4 bytes)
  //        data: const = 0x0 (8 bytes)
  //      }
  //    }
  //  ]
  NONFAILING(*(uint32_t*)0x200004c0 = 0xb0002016);
  NONFAILING(*(uint64_t*)0x200004c4 = 0);
  syscall(__NR_epoll_ctl, /*epfd=*/r[0], /*op=*/1ul, /*fd=*/r[1],
          /*ev=*/0x200004c0ul);
  //  epoll_pwait2 arguments: [
  //    epfd: fd_epoll (resource)
  //    events: ptr[out, array[epoll_event]] {
  //      array[epoll_event] {
  //        epoll_event {
  //          ev: epoll_ev = 0x0 (4 bytes)
  //          data: const = 0x0 (8 bytes)
  //        }
  //      }
  //    }
  //    maxevents: len = 0x1 (8 bytes)
  //    timeout: nil
  //    sigmask: nil
  //    size: bytesize = 0x0 (8 bytes)
  //  ]
  syscall(__NR_epoll_pwait2, /*epfd=*/r[0], /*events=*/0x20000280ul,
          /*maxevents=*/1ul, /*timeout=*/0ul, /*sigmask=*/0ul, /*size=*/0ul);
  return 0;
}