syzkaller-repros/linux/45cf4865bc441624c0bea42d8e9dbdc2a8a0fa14.c

// KASAN: use-after-free Read in ip6_route_mpath_notify
// https://syzkaller.appspot.com/bug?id=45cf4865bc441624c0bea42d8e9dbdc2a8a0fa14
// status:fixed
// autogenerated by syzkaller (http://github.com/google/syzkaller)

#define _GNU_SOURCE
#include <arpa/inet.h>
#include <endian.h>
#include <errno.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/if.h>
#include <linux/if_ether.h>
#include <linux/if_tun.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <net/if_arp.h>
#include <sched.h>
#include <signal.h>
#include <stdarg.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/prctl.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/time.h>
#include <sys/uio.h>
#include <sys/wait.h>
#include <unistd.h>

__attribute__((noreturn)) static void doexit(int status)
{
  volatile unsigned i;
  syscall(__NR_exit_group, status);
  for (i = 0;; i++) {
  }
}
#include <errno.h>
#include <stdarg.h>
#include <stdint.h>
#include <stdio.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 void vsnprintf_check(char* str, size_t size, const char* format,
                            va_list args)
{
  int rv;

  rv = vsnprintf(str, size, format, args);
  if (rv < 0)
    fail("tun: snprintf failed");
  if ((size_t)rv >= size)
    fail("tun: string '%s...' doesn't fit into buffer", str);
}

#define COMMAND_MAX_LEN 128
#define PATH_PREFIX                                                            \
  "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin "
#define PATH_PREFIX_LEN (sizeof(PATH_PREFIX) - 1)

static void execute_command(bool panic, const char* format, ...)
{
  va_list args;
  char command[PATH_PREFIX_LEN + COMMAND_MAX_LEN];
  int rv;

  va_start(args, format);
  memcpy(command, PATH_PREFIX, PATH_PREFIX_LEN);
  vsnprintf_check(command + PATH_PREFIX_LEN, COMMAND_MAX_LEN, format, args);
  va_end(args);
  rv = system(command);
  if (rv) {
    if (panic)
      fail("command '%s' failed: %d", &command[0], rv);
  }
}

static int tunfd = -1;
static int tun_frags_enabled;

#define SYZ_TUN_MAX_PACKET_SIZE 1000

#define TUN_IFACE "syz_tun"

#define LOCAL_MAC "aa:aa:aa:aa:aa:aa"
#define REMOTE_MAC "aa:aa:aa:aa:aa:bb"

#define LOCAL_IPV4 "172.20.20.170"
#define REMOTE_IPV4 "172.20.20.187"

#define LOCAL_IPV6 "fe80::aa"
#define REMOTE_IPV6 "fe80::bb"

#define IFF_NAPI 0x0010
#define IFF_NAPI_FRAGS 0x0020

static void initialize_tun(void)
{
  tunfd = open("/dev/net/tun", O_RDWR | O_NONBLOCK);
  if (tunfd == -1) {
    printf("tun: can't open /dev/net/tun: please enable CONFIG_TUN=y\n");
    printf("otherwise fuzzing or reproducing might not work as intended\n");
    return;
  }
  const int kTunFd = 252;
  if (dup2(tunfd, kTunFd) < 0)
    fail("dup2(tunfd, kTunFd) failed");
  close(tunfd);
  tunfd = kTunFd;

  struct ifreq ifr;
  memset(&ifr, 0, sizeof(ifr));
  strncpy(ifr.ifr_name, TUN_IFACE, IFNAMSIZ);
  ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_NAPI | IFF_NAPI_FRAGS;
  if (ioctl(tunfd, TUNSETIFF, (void*)&ifr) < 0) {
    ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
    if (ioctl(tunfd, TUNSETIFF, (void*)&ifr) < 0)
      fail("tun: ioctl(TUNSETIFF) failed");
  }
  if (ioctl(tunfd, TUNGETIFF, (void*)&ifr) < 0)
    fail("tun: ioctl(TUNGETIFF) failed");
  tun_frags_enabled = (ifr.ifr_flags & IFF_NAPI_FRAGS) != 0;

  execute_command(1, "sysctl -w net.ipv6.conf.%s.accept_dad=0", TUN_IFACE);

  execute_command(1, "sysctl -w net.ipv6.conf.%s.router_solicitations=0",
                  TUN_IFACE);

  execute_command(1, "ip link set dev %s address %s", TUN_IFACE, LOCAL_MAC);
  execute_command(1, "ip addr add %s/24 dev %s", LOCAL_IPV4, TUN_IFACE);
  execute_command(1, "ip -6 addr add %s/120 dev %s", LOCAL_IPV6, TUN_IFACE);
  execute_command(1, "ip neigh add %s lladdr %s dev %s nud permanent",
                  REMOTE_IPV4, REMOTE_MAC, TUN_IFACE);
  execute_command(1, "ip -6 neigh add %s lladdr %s dev %s nud permanent",
                  REMOTE_IPV6, REMOTE_MAC, TUN_IFACE);
  execute_command(1, "ip link set dev %s up", TUN_IFACE);
}

#define DEV_IPV4 "172.20.20.%d"
#define DEV_IPV6 "fe80::%02hx"
#define DEV_MAC "aa:aa:aa:aa:aa:%02hx"

static void snprintf_check(char* str, size_t size, const char* format, ...)
{
  va_list args;

  va_start(args, format);
  vsnprintf_check(str, size, format, args);
  va_end(args);
}

static void initialize_netdevices(void)
{
  unsigned i;
  const char* devtypes[] = {"ip6gretap", "bridge", "vcan", "bond", "team"};
  const char* devnames[] = {"lo",
                            "sit0",
                            "bridge0",
                            "vcan0",
                            "tunl0",
                            "gre0",
                            "gretap0",
                            "ip_vti0",
                            "ip6_vti0",
                            "ip6tnl0",
                            "ip6gre0",
                            "ip6gretap0",
                            "erspan0",
                            "bond0",
                            "veth0",
                            "veth1",
                            "team0",
                            "veth0_to_bridge",
                            "veth1_to_bridge",
                            "veth0_to_bond",
                            "veth1_to_bond",
                            "veth0_to_team",
                            "veth1_to_team"};
  const char* devmasters[] = {"bridge", "bond", "team"};

  for (i = 0; i < sizeof(devtypes) / (sizeof(devtypes[0])); i++)
    execute_command(0, "ip link add dev %s0 type %s", devtypes[i], devtypes[i]);
  execute_command(0, "ip link add type veth");

  for (i = 0; i < sizeof(devmasters) / (sizeof(devmasters[0])); i++) {
    execute_command(
        0, "ip link add name %s_slave_0 type veth peer name veth0_to_%s",
        devmasters[i], devmasters[i]);
    execute_command(
        0, "ip link add name %s_slave_1 type veth peer name veth1_to_%s",
        devmasters[i], devmasters[i]);
    execute_command(0, "ip link set %s_slave_0 master %s0", devmasters[i],
                    devmasters[i]);
    execute_command(0, "ip link set %s_slave_1 master %s0", devmasters[i],
                    devmasters[i]);
    execute_command(0, "ip link set veth0_to_%s up", devmasters[i]);
    execute_command(0, "ip link set veth1_to_%s up", devmasters[i]);
  }
  execute_command(0, "ip link set bridge_slave_0 up");
  execute_command(0, "ip link set bridge_slave_1 up");

  for (i = 0; i < sizeof(devnames) / (sizeof(devnames[0])); i++) {
    char addr[32];
    snprintf_check(addr, sizeof(addr), DEV_IPV4, i + 10);
    execute_command(0, "ip -4 addr add %s/24 dev %s", addr, devnames[i]);
    snprintf_check(addr, sizeof(addr), DEV_IPV6, i + 10);
    execute_command(0, "ip -6 addr add %s/120 dev %s", addr, devnames[i]);
    snprintf_check(addr, sizeof(addr), DEV_MAC, i + 10);
    execute_command(0, "ip link set dev %s address %s", devnames[i], addr);
    execute_command(0, "ip link set dev %s up", devnames[i]);
  }
}

#define MAX_FRAGS 4
struct vnet_fragmentation {
  uint32_t full;
  uint32_t count;
  uint32_t frags[MAX_FRAGS];
};

static uintptr_t syz_emit_ethernet(uintptr_t a0, uintptr_t a1, uintptr_t a2)
{
  if (tunfd < 0)
    return (uintptr_t)-1;

  uint32_t length = a0;
  char* data = (char*)a1;

  struct vnet_fragmentation* frags = (struct vnet_fragmentation*)a2;
  struct iovec vecs[MAX_FRAGS + 1];
  uint32_t nfrags = 0;
  if (!tun_frags_enabled || frags == NULL) {
    vecs[nfrags].iov_base = data;
    vecs[nfrags].iov_len = length;
    nfrags++;
  } else {
    bool full = true;
    uint32_t i, count = 0;
    full = frags->full;
    count = frags->count;
    if (count > MAX_FRAGS)
      count = MAX_FRAGS;
    for (i = 0; i < count && length != 0; i++) {
      uint32_t size = 0;
      size = frags->frags[i];
      if (size > length)
        size = length;
      vecs[nfrags].iov_base = data;
      vecs[nfrags].iov_len = size;
      nfrags++;
      data += size;
      length -= size;
    }
    if (length != 0 && (full || nfrags == 0)) {
      vecs[nfrags].iov_base = data;
      vecs[nfrags].iov_len = length;
      nfrags++;
    }
  }
  return writev(tunfd, vecs, nfrags);
}

static void loop();

static void sandbox_common()
{
  prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
  setpgrp();
  setsid();

  struct rlimit rlim;
  rlim.rlim_cur = rlim.rlim_max = 160 << 20;
  setrlimit(RLIMIT_AS, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 8 << 20;
  setrlimit(RLIMIT_MEMLOCK, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 136 << 20;
  setrlimit(RLIMIT_FSIZE, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 1 << 20;
  setrlimit(RLIMIT_STACK, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 0;
  setrlimit(RLIMIT_CORE, &rlim);

  if (unshare(CLONE_NEWNS)) {
  }
  if (unshare(CLONE_NEWIPC)) {
  }
  if (unshare(0x02000000)) {
  }
  if (unshare(CLONE_NEWUTS)) {
  }
  if (unshare(CLONE_SYSVSEM)) {
  }
}

static int do_sandbox_none(void)
{
  if (unshare(CLONE_NEWPID)) {
  }
  int pid = fork();
  if (pid < 0)
    fail("sandbox fork failed");
  if (pid)
    return pid;

  sandbox_common();
  if (unshare(CLONE_NEWNET)) {
  }
  initialize_tun();
  initialize_netdevices();
  loop();
  doexit(1);
}

static void execute_one();
extern unsigned long long procid;

void loop()
{
  while (1) {
    execute_one();
  }
}

uint64_t r[1] = {0xffffffffffffffff};
void execute_one()
{
  long res = 0;
  res = syscall(__NR_socket, 0x10, 0x8000000000000003, 0);
  if (res != -1)
    r[0] = res;
  *(uint64_t*)0x20000080 = 0x200000c0;
  *(uint16_t*)0x200000c0 = 0x10;
  *(uint16_t*)0x200000c2 = 0;
  *(uint32_t*)0x200000c4 = 0;
  *(uint32_t*)0x200000c8 = 0;
  *(uint32_t*)0x20000088 = 0x80;
  *(uint64_t*)0x20000090 = 0x20014000;
  *(uint64_t*)0x20014000 = 0x20014f79;
  memcpy((void*)0x20014f79,
         "\x55\x00\x00\x00\x18\x00\x7f\xcd\xb7\x2d\x1c\xb2\xa4\xa2\x80\xa8\x0a"
         "\x06\x05\x00\x00\xa8\x43\x02\x91\x05\x23\x69\x25\x00\x09\x00\x08\x00"
         "\x00\x1c\x01\x00\x00\x00\x14\x00\xa3\x07\x0d\x00\x00\x00\x03\x00\x00"
         "\xdc\x13\x38\xd5\x44\x00\x00\x9b\x84\x22\x6e\xb7\x5a\xfb\x83\xde\x44"
         "\x8d\xaa\x72\x27\xc4\x3a\xb8\x22\x00\x00\x06\x0c\xec\x4f\x8b\x91\xd4",
         85);
  *(uint64_t*)0x20014008 = 0x55;
  *(uint64_t*)0x20000098 = 1;
  *(uint64_t*)0x200000a0 = 0x20000080;
  *(uint64_t*)0x200000a8 = 0;
  *(uint32_t*)0x200000b0 = 0;
  syscall(__NR_sendmsg, r[0], 0x20000080, 0);
  *(uint32_t*)0x20000100 = 0x41424344;
  *(uint32_t*)0x20000104 = 0x41424344;
  *(uint32_t*)0x200002c0 = 0;
  *(uint32_t*)0x200002c4 = 0;
  *(uint32_t*)0x200002c8 = 0;
  *(uint32_t*)0x200002cc = 0;
  *(uint32_t*)0x200002d0 = 0;
  *(uint32_t*)0x200002d4 = 0;
  syz_emit_ethernet(4, 0x20000100, 0x200002c0);
}

int main()
{
  syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0);
  for (;;) {
    int pid = do_sandbox_none();
    int status = 0;
    while (waitpid(pid, &status, __WALL) != pid) {
    }
  }
}