syzkaller-repros/linux/5a9a2222721209075f5c34688bbcbb9d0c23d1b3.c

// possible deadlock in ovl_write_iter
// https://syzkaller.appspot.com/bug?id=5a9a2222721209075f5c34688bbcbb9d0c23d1b3
// status:dup
// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE

#include <endian.h>
#include <pthread.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 <time.h>
#include <unistd.h>

#include <linux/futex.h>

static __thread int skip_segv;
static __thread jmp_buf segv_env;

static void segv_handler(int sig, siginfo_t* info, void* ctx)
{
  uintptr_t addr = (uintptr_t)info->si_addr;
  const uintptr_t prog_start = 1 << 20;
  const uintptr_t prog_end = 100 << 20;
  if (__atomic_load_n(&skip_segv, __ATOMIC_RELAXED) &&
      (addr < prog_start || addr > prog_end)) {
    _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(...)                                                        \
  {                                                                            \
    __atomic_fetch_add(&skip_segv, 1, __ATOMIC_SEQ_CST);                       \
    if (_setjmp(segv_env) == 0) {                                              \
      __VA_ARGS__;                                                             \
    }                                                                          \
    __atomic_fetch_sub(&skip_segv, 1, __ATOMIC_SEQ_CST);                       \
  }

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

static uint64_t current_time_ms(void)
{
  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 | FUTEX_PRIVATE_FLAG);
}

static void event_wait(event_t* ev)
{
  while (!__atomic_load_n(&ev->state, __ATOMIC_ACQUIRE))
    syscall(SYS_futex, &ev->state, FUTEX_WAIT | FUTEX_PRIVATE_FLAG, 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 | FUTEX_PRIVATE_FLAG, 0, &ts);
    if (__atomic_load_n(&ev->state, __ATOMIC_RELAXED))
      return 1;
    now = current_time_ms();
    if (now - start > timeout)
      return 0;
  }
}

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 loop(void)
{
  int i, call, thread;
  int collide = 0;
again:
  for (call = 0; call < 9; call++) {
    for (thread = 0; thread < (int)(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);
      if (collide && (call % 2) == 0)
        break;
      event_timedwait(&th->done, 45);
      break;
    }
  }
  for (i = 0; i < 100 && __atomic_load_n(&running, __ATOMIC_RELAXED); i++)
    sleep_ms(1);
  if (!collide) {
    collide = 1;
    goto again;
  }
}

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

void execute_call(int call)
{
  long res;
  switch (call) {
  case 0:
    NONFAILING(memcpy((void*)0x20000140, "./file1", 8));
    syscall(__NR_mkdir, 0x20000140, 0);
    break;
  case 1:
    NONFAILING(memcpy((void*)0x20000180, "./file0", 8));
    syscall(__NR_mkdir, 0x20000180, 0);
    break;
  case 2:
    NONFAILING(memcpy((void*)0x20000000, "./file0", 8));
    NONFAILING(memcpy((void*)0x200000c0, "overlay", 8));
    NONFAILING(memcpy((void*)0x20000c40,
                      "upperdir=./file0,lowerdir=./file1,workdir=./file1", 49));
    syscall(__NR_mount, 0x400000, 0x20000000, 0x200000c0, 0, 0x20000c40);
    break;
  case 3:
    res = syscall(__NR_pipe, 0x20000240);
    if (res != -1) {
      NONFAILING(r[0] = *(uint32_t*)0x20000240);
      NONFAILING(r[1] = *(uint32_t*)0x20000244);
    }
    break;
  case 4:
    NONFAILING(memcpy((void*)0x200000c0, "memory.events", 14));
    syscall(__NR_openat, 0xffffff9c, 0x200000c0, 0x26e1, 0);
    break;
  case 5:
    NONFAILING(memcpy((void*)0x20000140, "memory.events", 14));
    res = syscall(__NR_openat, 0xffffff9c, 0x20000140, 0x7a05, 0x1700);
    if (res != -1)
      r[2] = res;
    break;
  case 6:
    syscall(__NR_write, r[1], 0x20000140, 0xfffffc8f);
    break;
  case 7:
    syscall(__NR_splice, r[0], 0, r[2], 0, 0x100000000000a, 7);
    break;
  case 8:
    NONFAILING(memcpy((void*)0x20000280, "./file0", 8));
    syscall(__NR_chdir, 0x20000280);
    break;
  }
}
int main(void)
{
  syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0);
  install_segv_handler();
  loop();
  return 0;
}