syzkaller-repros/linux/6c86f8057d87186f6b9dd52ed247f5e5781d142f.c

// INFO: rcu detected stall in tty_ioctl
// https://syzkaller.appspot.com/bug?id=6c86f8057d87186f6b9dd52ed247f5e5781d142f
// status:fixed
// autogenerated by syzkaller (http://github.com/google/syzkaller)

#define _GNU_SOURCE

#include <endian.h>
#include <fcntl.h>
#include <linux/futex.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <unistd.h>

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

static uintptr_t syz_open_pts(uintptr_t a0, uintptr_t a1)
{
  int ptyno = 0;
  if (ioctl(a0, TIOCGPTN, &ptyno))
    return -1;
  char buf[128];
  sprintf(buf, "/dev/pts/%d", ptyno);
  return open(buf, a1, 0);
}

static void test();

void loop()
{
  while (1) {
    test();
  }
}

struct thread_t {
  int created, running, call;
  pthread_t th;
};

static struct thread_t threads[16];
static void execute_call(int call);
static int running;
static int collide;

static void* thr(void* arg)
{
  struct thread_t* th = (struct thread_t*)arg;
  for (;;) {
    while (!__atomic_load_n(&th->running, __ATOMIC_ACQUIRE))
      syscall(SYS_futex, &th->running, FUTEX_WAIT, 0, 0);
    execute_call(th->call);
    __atomic_fetch_sub(&running, 1, __ATOMIC_RELAXED);
    __atomic_store_n(&th->running, 0, __ATOMIC_RELEASE);
    syscall(SYS_futex, &th->running, FUTEX_WAKE);
  }
  return 0;
}

static void execute(int num_calls)
{
  int call, thread;
  running = 0;
  for (call = 0; call < num_calls; call++) {
    for (thread = 0; thread < sizeof(threads) / sizeof(threads[0]);
         thread++) {
      struct thread_t* th = &threads[thread];
      if (!th->created) {
        th->created = 1;
        pthread_attr_t attr;
        pthread_attr_init(&attr);
        pthread_attr_setstacksize(&attr, 128 << 10);
        pthread_create(&th->th, &attr, thr, th);
      }
      if (!__atomic_load_n(&th->running, __ATOMIC_ACQUIRE)) {
        th->call = call;
        __atomic_fetch_add(&running, 1, __ATOMIC_RELAXED);
        __atomic_store_n(&th->running, 1, __ATOMIC_RELEASE);
        syscall(SYS_futex, &th->running, FUTEX_WAKE);
        if (collide && call % 2)
          break;
        struct timespec ts;
        ts.tv_sec = 0;
        ts.tv_nsec = 20 * 1000 * 1000;
        syscall(SYS_futex, &th->running, FUTEX_WAIT, 1, &ts);
        if (running)
          usleep((call == num_calls - 1) ? 10000 : 1000);
        break;
      }
    }
  }
}

long r[2];
uint64_t procid;
void execute_call(int call)
{
  switch (call) {
  case 0:
    syscall(__NR_mmap, 0x20000000, 0xfff000, 0x3, 0x32, 0xffffffff,
            0x0);
    break;
  case 1:
    memcpy((void*)0x20fe4000, "/dev/ptmx", 10);
    r[0] = syscall(__NR_openat, 0xffffffffffffff9c, 0x20fe4000, 0x400,
                   0x0);
    break;
  case 2:
    *(uint16_t*)0x20fd6000 = 0x0;
    *(uint16_t*)0x20fd6002 = 0x0;
    *(uint16_t*)0x20fd6004 = 0x0;
    *(uint16_t*)0x20fd6006 = 0x0;
    *(uint8_t*)0x20fd6008 = 0x0;
    *(uint8_t*)0x20fd6009 = 0x0;
    *(uint8_t*)0x20fd600a = 0x0;
    *(uint8_t*)0x20fd600b = 0x0;
    *(uint32_t*)0x20fd600c = 0xfffffff7;
    *(uint8_t*)0x20fd6010 = 0x0;
    syscall(__NR_ioctl, r[0], 0x5402, 0x20fd6000);
    break;
  case 3:
    *(uint32_t*)0x203fffdc = 0x0;
    *(uint32_t*)0x203fffe0 = 0x1;
    *(uint32_t*)0x203fffe4 = 0x2b;
    *(uint32_t*)0x203fffe8 = 0xfffffff8;
    *(uint8_t*)0x203fffec = 0x6;
    *(uint8_t*)0x203fffed = 0x7;
    *(uint8_t*)0x203fffee = 0x0;
    *(uint8_t*)0x203fffef = 0xfe;
    *(uint32_t*)0x203ffff0 = 0x0;
    *(uint32_t*)0x203ffff4 = 0x0;
    *(uint32_t*)0x203ffff8 = 0x0;
    *(uint32_t*)0x203ffffc = 0x69953b77;
    syscall(__NR_ioctl, r[0], 0x40045431, 0x203fffdc);
    break;
  case 4:
    r[1] = syz_open_pts(r[0], 0x0);
    break;
  case 5:
    syscall(__NR_ioctl, r[1], 0x541b, 0x20a6bffc);
    break;
  case 6:
    *(uint64_t*)0x20fd6000 = 0x20313f29;
    *(uint64_t*)0x20fd6008 = 0x1;
    syscall(__NR_readv, r[1], 0x20fd6000, 0x1);
    break;
  case 7:
    syscall(__NR_ioctl, r[0], 0x540a, 0x2);
    break;
  }
}

void test()
{
  memset(r, -1, sizeof(r));
  execute(8);
  collide = 1;
  execute(8);
}

int main()
{
  int i;
  for (i = 0; i < 8; i++) {
    if (fork() == 0) {
      procid = i;
      loop();
      return 0;
    }
  }
  sleep(1000000);
  return 0;
}