syzkaller-repros/linux/4cd28c5d3edf64c32bdf0bde64960b52d6b5d51b.c

// BUG: unable to handle kernel NULL pointer dereference in l2tp_session_free
// https://syzkaller.appspot.com/bug?id=4cd28c5d3edf64c32bdf0bde64960b52d6b5d51b
// status:open
// autogenerated by syzkaller (http://github.com/google/syzkaller)

#define _GNU_SOURCE
#include <endian.h>
#include <errno.h>
#include <linux/futex.h>
#include <linux/net.h>
#include <netinet/in.h>
#include <pthread.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/prctl.h>
#include <sys/socket.h>
#include <sys/syscall.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

__attribute__((noreturn)) static void doexit(int status)
{
  volatile unsigned i;
  syscall(__NR_exit_group, status);
  for (i = 0;; i++) {
  }
}
#include <stdint.h>
#include <string.h>

const int kFailStatus = 67;
const int kRetryStatus = 69;

static void fail(const char* msg, ...)
{
  int e = errno;
  va_list args;
  va_start(args, msg);
  vfprintf(stderr, msg, args);
  va_end(args);
  fprintf(stderr, " (errno %d)\n", e);
  doexit((e == ENOMEM || e == EAGAIN) ? kRetryStatus : kFailStatus);
}

static uint64_t current_time_ms()
{
  struct timespec ts;

  if (clock_gettime(CLOCK_MONOTONIC, &ts))
    fail("clock_gettime failed");
  return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}

struct ipt_getinfo {
  char name[32];
  unsigned int valid_hooks;
  unsigned int hook_entry[5];
  unsigned int underflow[5];
  unsigned int num_entries;
  unsigned int size;
};

struct ipt_get_entries {
  char name[32];
  unsigned int size;
  void* entrytable[1024 / sizeof(void*)];
};

struct xt_counters {
  uint64_t pcnt, bcnt;
};

struct ipt_replace {
  char name[32];
  unsigned int valid_hooks;
  unsigned int num_entries;
  unsigned int size;
  unsigned int hook_entry[5];
  unsigned int underflow[5];
  unsigned int num_counters;
  struct xt_counters* counters;
  char entrytable[1024];
};

struct ipt_table_desc {
  const char* name;
  struct ipt_getinfo info;
  struct ipt_get_entries entries;
  struct ipt_replace replace;
  struct xt_counters counters[10];
};

static struct ipt_table_desc ipv4_tables[] = {
    {.name = "filter"}, {.name = "nat"},      {.name = "mangle"},
    {.name = "raw"},    {.name = "security"},
};

#define IPT_BASE_CTL 64
#define IPT_SO_SET_REPLACE (IPT_BASE_CTL)
#define IPT_SO_GET_INFO (IPT_BASE_CTL)
#define IPT_SO_GET_ENTRIES (IPT_BASE_CTL + 1)

static void checkpoint_net_namespace(void)
{
  socklen_t optlen;
  unsigned i;
  int fd;

  fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
  if (fd == -1)
    fail("socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)");
  for (i = 0; i < sizeof(ipv4_tables) / sizeof(ipv4_tables[0]); i++) {
    struct ipt_table_desc* table = &ipv4_tables[i];
    strcpy(table->info.name, table->name);
    strcpy(table->entries.name, table->name);
    strcpy(table->replace.name, table->name);
    optlen = sizeof(table->info);
    if (getsockopt(fd, SOL_IP, IPT_SO_GET_INFO, &table->info, &optlen)) {
      switch (errno) {
      case EPERM:
      case ENOENT:
      case ENOPROTOOPT:
        continue;
      }
      fail("getsockopt(IPT_SO_GET_INFO)");
    }
    if (table->info.size > sizeof(table->entries.entrytable))
      fail("table size is too large: %u", table->info.size);
    if (table->info.num_entries >
        sizeof(table->counters) / sizeof(table->counters[0]))
      fail("too many counters: %u", table->info.num_entries);
    table->entries.size = table->info.size;
    optlen = sizeof(table->entries) - sizeof(table->entries.entrytable) +
             table->info.size;
    if (getsockopt(fd, SOL_IP, IPT_SO_GET_ENTRIES, &table->entries, &optlen))
      fail("getsockopt(IPT_SO_GET_ENTRIES)");
    table->replace.valid_hooks = table->info.valid_hooks;
    table->replace.num_entries = table->info.num_entries;
    table->replace.counters = table->counters;
    table->replace.size = table->info.size;
    memcpy(table->replace.hook_entry, table->info.hook_entry,
           sizeof(table->replace.hook_entry));
    memcpy(table->replace.underflow, table->info.underflow,
           sizeof(table->replace.underflow));
    memcpy(table->replace.entrytable, table->entries.entrytable,
           table->info.size);
  }
  close(fd);
}

static void reset_net_namespace(void)
{
  struct ipt_get_entries entries;
  struct ipt_getinfo info;
  socklen_t optlen;
  unsigned i;
  int fd;

  memset(&info, 0, sizeof(info));
  memset(&entries, 0, sizeof(entries));
  fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
  if (fd == -1)
    fail("socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)");
  for (i = 0; i < sizeof(ipv4_tables) / sizeof(ipv4_tables[0]); i++) {
    struct ipt_table_desc* table = &ipv4_tables[i];
    if (table->info.valid_hooks == 0)
      continue;
    strcpy(info.name, table->name);
    optlen = sizeof(info);
    if (getsockopt(fd, SOL_IP, IPT_SO_GET_INFO, &info, &optlen))
      fail("getsockopt(IPT_SO_GET_INFO)");
    if (memcmp(&table->info, &info, sizeof(table->info)) == 0) {
      strcpy(entries.name, table->name);
      entries.size = table->info.size;
      optlen = sizeof(entries) - sizeof(entries.entrytable) + entries.size;
      if (getsockopt(fd, SOL_IP, IPT_SO_GET_ENTRIES, &entries, &optlen))
        fail("getsockopt(IPT_SO_GET_ENTRIES)");
      if (memcmp(&table->entries, &entries, optlen) == 0)
        continue;
    }
    table->replace.num_counters = info.num_entries;
    optlen = sizeof(table->replace) - sizeof(table->replace.entrytable) +
             table->replace.size;
    if (setsockopt(fd, SOL_IP, IPT_SO_SET_REPLACE, &table->replace, optlen))
      fail("setsockopt(IPT_SO_SET_REPLACE)");
  }
  close(fd);
}

static void test();

void loop()
{
  int iter;
  checkpoint_net_namespace();
  for (iter = 0;; iter++) {
    int pid = fork();
    if (pid < 0)
      fail("loop fork failed");
    if (pid == 0) {
      prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
      setpgrp();
      test();
      doexit(0);
    }
    int status = 0;
    uint64_t start = current_time_ms();
    for (;;) {
      int res = waitpid(-1, &status, __WALL | WNOHANG);
      if (res == pid)
        break;
      usleep(1000);
      if (current_time_ms() - start > 5 * 1000) {
        kill(-pid, SIGKILL);
        kill(pid, SIGKILL);
        while (waitpid(-1, &status, __WALL) != pid) {
        }
        break;
      }
    }
    reset_net_namespace();
  }
}

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

long r[7];
uint64_t procid;
void execute_call(int call)
{
  switch (call) {
  case 0:
    syscall(__NR_mmap, 0x20000000, 0xe7b000, 3, 0x32, -1, 0);
    break;
  case 1:
    memcpy((void*)0x20e7a000, "ceph", 5);
    *(uint8_t*)0x2052d000 = 0x73;
    *(uint8_t*)0x2052d001 = 0x79;
    *(uint8_t*)0x2052d002 = 0x7a;
    *(uint8_t*)0x2052d003 = 0x23 + procid * 4;
    *(uint8_t*)0x2052d004 = 0;
    memcpy((void*)0x20e7a000, "bdev/", 6);
    r[0] = syscall(__NR_request_key, 0x20e7a000, 0x2052d000, 0x20e7a000, -1);
    break;
  case 2:
    memcpy((void*)0x20aa2ff6, "blacklist", 10);
    *(uint8_t*)0x20e7affb = 0x73;
    *(uint8_t*)0x20e7affc = 0x79;
    *(uint8_t*)0x20e7affd = 0x7a;
    *(uint8_t*)0x20e7affe = 0x20 + procid * 4;
    *(uint8_t*)0x20e7afff = 0;
    memcpy((void*)0x20821fff, "", 1);
    r[1] = syscall(__NR_request_key, 0x20aa2ff6, 0x20e7affb, 0x20821fff,
                   0xfffffffd);
    break;
  case 3:
    syscall(__NR_keyctl, 0xc, r[0], 0x20b7df17, 0, r[1]);
    break;
  case 4:
    syscall(__NR_mmap, 0x20e7b000, 0x1000, 3, 0x32, -1, 0);
    break;
  case 5:
    memcpy((void*)0x20e7b000, "/selinux/policy", 16);
    r[2] = syscall(__NR_openat, 0xffffffffffffff9c, 0x20e7b000, 0, 0);
    break;
  case 6:
    syscall(__NR_mmap, 0x20e7b000, 0x1000, 3, 0x32, -1, 0);
    break;
  case 7:
    syscall(__NR_ioctl, r[2], 0x5411, 0x20e7bffc);
    break;
  case 8:
    memcpy((void*)0x20663000, "GPL*bdevself{GPL-user'/trustedtrusted%", 39);
    r[3] = syscall(__NR_memfd_create, 0x20663000, 2);
    break;
  case 9:
    syscall(__NR_ioctl, r[3], 0x4c81, 0);
    break;
  case 10:
    r[4] = syscall(__NR_socket, 0xa, 2, 0);
    break;
  case 11:
    r[5] = syscall(__NR_socket, 0x18, 1, 1);
    break;
  case 12:
    syscall(__NR_mmap, 0x20e7c000, 0x1000, 3, 0x32, -1, 0);
    break;
  case 13:
    memcpy((void*)0x20e7cff6, "blacklist", 10);
    syscall(__NR_memfd_create, 0x20e7cff6, 2);
    break;
  case 14:
    *(uint16_t*)0x20e71000 = 0x18;
    *(uint32_t*)0x20e71002 = 1;
    *(uint32_t*)0x20e71006 = 0;
    *(uint32_t*)0x20e7100a = r[4];
    *(uint16_t*)0x20e7100e = 3;
    *(uint16_t*)0x20e71010 = 0;
    *(uint16_t*)0x20e71012 = 3;
    *(uint16_t*)0x20e71014 = 0;
    *(uint16_t*)0x20e71016 = 0xa;
    *(uint16_t*)0x20e71018 = htobe16(0x4e22 + procid * 4);
    *(uint32_t*)0x20e7101a = 3;
    *(uint8_t*)0x20e7101e = 0xfe;
    *(uint8_t*)0x20e7101f = 0x80;
    *(uint8_t*)0x20e71020 = 0;
    *(uint8_t*)0x20e71021 = 0;
    *(uint8_t*)0x20e71022 = 0;
    *(uint8_t*)0x20e71023 = 0;
    *(uint8_t*)0x20e71024 = 0;
    *(uint8_t*)0x20e71025 = 0;
    *(uint8_t*)0x20e71026 = 0;
    *(uint8_t*)0x20e71027 = 0;
    *(uint8_t*)0x20e71028 = 0;
    *(uint8_t*)0x20e71029 = 0;
    *(uint8_t*)0x20e7102a = 0;
    *(uint8_t*)0x20e7102b = 0;
    *(uint8_t*)0x20e7102c = 0 + procid * 1;
    *(uint8_t*)0x20e7102d = 0xbb;
    *(uint32_t*)0x20e7102e = 4;
    syscall(__NR_connect, r[5], 0x20e71000, 0x32);
    break;
  case 15:
    r[6] = syscall(__NR_socket, 0x18, 1, 1);
    break;
  case 16:
    memcpy((void*)0x20c83fd6, "system_u:object_r:semanage_read_lock_t:s0", 42);
    syscall(__NR_write, r[3], 0x20c83fd6, 0x2a);
    break;
  case 17:
    syscall(__NR_close, r[4]);
    break;
  case 18:
    syscall(__NR_dup2, r[6], r[5]);
    break;
  }
}

void test()
{
  memset(r, -1, sizeof(r));
  execute(19);
  collide = 1;
  execute(19);
}

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