repro.c

#define _GNU_SOURCE

#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/futex.h>
#include <pthread.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

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);
  int i = 0;
  for (; i < 100; i++) {
    if (pthread_create(&th, &attr, fn, arg) == 0) {
      pthread_attr_destroy(&attr);
      return;
    }
    if (errno == EAGAIN) {
      usleep(50);
      continue;
    }
    break;
  }
  exit(1);
}

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, 1000000);
}

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_ACQUIRE)) return 1;
    now = current_time_ms();
    if (now - start > timeout) return 0;
  }
}

static bool write_file(const char* file, const char* what, ...) {
  char buf[1024];
  va_list args;
  va_start(args, what);
  vsnprintf(buf, sizeof(buf), what, args);
  va_end(args);
  buf[sizeof(buf) - 1] = 0;
  int len = strlen(buf);
  int fd = open(file, O_WRONLY | O_CLOEXEC);
  if (fd == -1) return false;
  if (write(fd, buf, len) != len) {
    int err = errno;
    close(fd);
    errno = err;
    return false;
  }
  close(fd);
  return true;
}

static void kill_and_wait(int pid, int* status) {
  kill(-pid, SIGKILL);
  kill(pid, SIGKILL);
  for (int i = 0; i < 100; i++) {
    if (waitpid(-1, status, WNOHANG | __WALL) == pid) return;
    usleep(1000);
  }
  DIR* dir = opendir("/sys/fs/fuse/connections");
  if (dir) {
    for (;;) {
      struct dirent* ent = readdir(dir);
      if (!ent) break;
      if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0)
        continue;
      char abort[300];
      snprintf(abort, sizeof(abort), "/sys/fs/fuse/connections/%s/abort",
               ent->d_name);
      int fd = open(abort, O_WRONLY);
      if (fd == -1) {
        continue;
      }
      if (write(fd, abort, 1) < 0) {
      }
      close(fd);
    }
    closedir(dir);
  } else {
  }
  while (waitpid(-1, status, __WALL) != pid) {
  }
}

static void setup_test() {
  prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
  setpgrp();
  write_file("/proc/self/oom_score_adj", "1000");
}

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(void) {
  int i, call, thread;
  for (call = 0; call < 6; 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);
      event_timedwait(&th->done, 50);
      break;
    }
  }
  for (i = 0; i < 100 && __atomic_load_n(&running, __ATOMIC_RELAXED); i++)
    sleep_ms(1);
}

static void execute_one(void);

#define WAIT_FLAGS __WALL

static void loop(void) {
  int iter = 0;
  for (;; iter++) {
    int pid = fork();
    if (pid < 0) exit(1);
    if (pid == 0) {
      setup_test();
      execute_one();
      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 < 5000) continue;
      kill_and_wait(pid, &status);
      break;
    }
  }
}

uint64_t r[2] = {0xffffffffffffffff, 0xffffffffffffffff};

void execute_call(int call) {
  intptr_t res = 0;
  switch (call) {
    case 0:
      memcpy((void*)0x20000280, "./file0\000", 8);
      res = syscall(__NR_creat, /*file=*/0x20000280ul,
                    /*mode=*/0xecf86c37d53049ccul);
      if (res != -1) r[0] = res;
      break;
    case 1:
      *(uint8_t*)0x20000440 = 0x7f;
      *(uint8_t*)0x20000441 = 0x45;
      *(uint8_t*)0x20000442 = 0x4c;
      *(uint8_t*)0x20000443 = 0x46;
      *(uint8_t*)0x20000444 = 0;
      *(uint8_t*)0x20000445 = 0;
      *(uint8_t*)0x20000446 = 0;
      *(uint8_t*)0x20000447 = 0;
      *(uint64_t*)0x20000448 = 0;
      *(uint16_t*)0x20000450 = 2;
      *(uint16_t*)0x20000452 = 0x3e;
      *(uint32_t*)0x20000454 = 0;
      *(uint32_t*)0x20000458 = 0;
      *(uint32_t*)0x2000045c = 0x38;
      *(uint32_t*)0x20000460 = 0;
      *(uint32_t*)0x20000464 = 0;
      *(uint16_t*)0x20000468 = 0xeb0;
      *(uint16_t*)0x2000046a = 0x20;
      *(uint16_t*)0x2000046c = 2;
      *(uint16_t*)0x2000046e = 0;
      *(uint16_t*)0x20000470 = 0;
      *(uint16_t*)0x20000472 = 0;
      *(uint32_t*)0x20000478 = 0;
      *(uint32_t*)0x2000047c = 0;
      *(uint32_t*)0x20000480 = 0;
      *(uint32_t*)0x20000484 = 0;
      *(uint32_t*)0x20000488 = 0;
      *(uint32_t*)0x2000048c = 0;
      *(uint32_t*)0x20000490 = 0;
      *(uint32_t*)0x20000494 = 0;
      memset((void*)0x20000498, 0, 256);
      memset((void*)0x20000598, 0, 256);
      memset((void*)0x20000698, 0, 256);
      memset((void*)0x20000798, 0, 256);
      memset((void*)0x20000898, 0, 256);
      memset((void*)0x20000998, 0, 256);
      memset((void*)0x20000a98, 0, 256);
      syscall(__NR_write, /*fd=*/r[0], /*data=*/0x20000440ul, /*len=*/0x758ul);
      break;
    case 2:
      syscall(__NR_close, /*fd=*/r[0]);
      break;
    case 3:
      memcpy((void*)0x20000000, "/dev/vhost-net\000", 15);
      res = syscall(__NR_openat, /*fd=*/0xffffffffffffff9cul,
                    /*file=*/0x20000000ul, /*flags=*/2ul, /*mode=*/0ul);
      if (res != -1) r[1] = res;
      break;
    case 4:
      syscall(__NR_ioctl, /*fd=*/r[1], /*cmd=*/0xaf01, /*v=*/0ul);
      break;
    case 5:
      memcpy((void*)0x20000400, "./file0\000", 8);
      syscall(__NR_execve, /*file=*/0x20000400ul, /*argv=*/0ul, /*envp=*/0ul);
      break;
  }
}
int main(void) {
  syscall(__NR_mmap, /*addr=*/0x1ffff000ul, /*len=*/0x1000ul, /*prot=*/0ul,
          /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);
  syscall(__NR_mmap, /*addr=*/0x20000000ul, /*len=*/0x1000000ul, /*prot=*/7ul,
          /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);
  syscall(__NR_mmap, /*addr=*/0x21000000ul, /*len=*/0x1000ul, /*prot=*/0ul,
          /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);
  loop();
  return 0;
}

repro.txt

r0 = creat(&(0x7f0000000280)='./file0\x00', 0xecf86c37d53049cc)
write$binfmt_elf32(r0, &(0x7f0000000440)={{0x7f, 0x45, 0x4c, 0x46, 0x0, 0x0, 0x0, 0x0, 0x0, 0x2, 0x3e, 0x0, 0x0, 0x38, 0x0, 0x0, 0xeb0, 0x20, 0x2}, [{}], "", ['\x00', '\x00', '\x00', '\x00', '\x00', '\x00', '\x00']}, 0x758)
close(r0)
r1 = openat$vnet(0xffffffffffffff9c, &(0x7f0000000000), 0x2, 0x0)
ioctl$int_in(r1, 0x40000000af01, 0x0)
execve(&(0x7f0000000400)='./file0\x00', 0x0, 0x0)