syzkaller-repros/linux/8b52ed117d693d904fde03433ca94c91089ea4ce.c

// KASAN: use-after-free Read in refcount_inc_not_zero
// https://syzkaller.appspot.com/bug?id=8b52ed117d693d904fde03433ca94c91089ea4ce
// status:invalid
// autogenerated by syzkaller (http://github.com/google/syzkaller)

#define _GNU_SOURCE

#include <endian.h>
#include <errno.h>
#include <sched.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <sys/prctl.h>
#include <sys/resource.h>
#include <sys/syscall.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <unistd.h>

__attribute__((noreturn)) static void doexit(int status)
{
  volatile unsigned i;
  syscall(__NR_exit_group, status);
  for (i = 0;; i++) {
  }
}

#include <stdint.h>
#include <string.h>

const int kFailStatus = 67;
const int kRetryStatus = 69;

static void fail(const char* msg, ...)
{
  int e = errno;
  va_list args;
  va_start(args, msg);
  vfprintf(stderr, msg, args);
  va_end(args);
  fprintf(stderr, " (errno %d)\n", e);
  doexit((e == ENOMEM || e == EAGAIN) ? kRetryStatus : kFailStatus);
}

static void loop();

static void sandbox_common()
{
  prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
  setpgrp();
  setsid();

  struct rlimit rlim;
  rlim.rlim_cur = rlim.rlim_max = 128 << 20;
  setrlimit(RLIMIT_AS, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 8 << 20;
  setrlimit(RLIMIT_MEMLOCK, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 1 << 20;
  setrlimit(RLIMIT_FSIZE, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 1 << 20;
  setrlimit(RLIMIT_STACK, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 0;
  setrlimit(RLIMIT_CORE, &rlim);

#define CLONE_NEWCGROUP 0x02000000

  unshare(CLONE_NEWNS);
  unshare(CLONE_NEWIPC);
  unshare(CLONE_NEWCGROUP);
  unshare(CLONE_NEWNET);
  unshare(CLONE_NEWUTS);
  unshare(CLONE_SYSVSEM);
}

static int do_sandbox_none(int executor_pid, bool enable_tun)
{
  unshare(CLONE_NEWPID);
  int pid = fork();
  if (pid < 0)
    fail("sandbox fork failed");
  if (pid)
    return pid;

  sandbox_common();

  loop();
  doexit(1);
}

void loop()
{
  syscall(__NR_mmap, 0x20000000, 0xfff000, 0x3, 0x32, 0xffffffff, 0x0);
  syscall(__NR_unshare, 0x8000000);
  memcpy((void*)0x20dda000, "./file0", 8);
  syscall(__NR_mkdir, 0x20dda000, 0x0);
  memcpy((void*)0x20900ff8, "./file0", 8);
  memcpy((void*)0x2001c000, "./file0", 8);
  memcpy((void*)0x20982ff9, "mqueue", 7);
  syscall(__NR_mount, 0x20900ff8, 0x2001c000, 0x20982ff9, 0x0,
          0x20ebcffe);
  memcpy((void*)0x20c5eff4, "./file0/bus", 12);
  syscall(__NR_creat, 0x20c5eff4, 0x0);
}

int main()
{
  int pid = do_sandbox_none(0, false);
  int status = 0;
  while (waitpid(pid, &status, __WALL) != pid) {
  }
  return 0;
}