Examples of errors detected by the V654 diagnostic

V654. Condition of a loop is always true/false.

Captain Blood

V654 [CWE-834] The condition 'n >= 0' of loop is always true. resourceselect.cpp 42

typedef unsigned int dword;

TResourceSelectorWindow::TResourceSelectorWindow ()
{
  string PakPath;
  // ....
  miss->EditorGetPackPath(PakPath);
  //....
  for (dword n = PakPath.Size()-1; n >= 0; n--)
  {
    if (PakPath[n] == '\\')
    {
      PakPath.Delete(0, n+1);
      break;
    }
  }

  // ....
}

FlipperZero

V654 [CWE-834] The condition '!done' of loop is always true. ibutton-cli.cpp 253

void onewire_cli_search(Cli* cli) {
  ....
  bool done = false;
  ....
  while(!done) {
    if(onewire.search(address, true) != 1) {
      printf("Search finished\r\n");
      onewire.reset_search();
      done = true;
      return;
    } else {
      printf("Found: ");
      for(uint8_t i = 0; i < 8; i++) {
        printf("%02X", address[i]);
      }
    printf("\r\n");
    }
    delay(100);
  }
  ....
}

TheXTech

V654 The condition 'chunk_size > 0' of loop is always true. thextech image_size.cpp 211

static bool tryJPEG(SDL_RWops* file, uint32_t *w, uint32_t *h)
{
  ....
  size_t chunk_size = 0;
  ....
  do
  {
    SDL_memset(raw, 0, JPEG_BUFFER_SIZE);
    pos = SDL_RWtell(file);
    chunk_size = SDL_RWread(file, raw, 1, JPEG_BUFFER_SIZE);
    if(chunk_size == 0)
      break;

    head = findJpegHead(raw, JPEG_BUFFER_SIZE);
    if(head)
    {
      if(head + 20 >= raw + JPEG_BUFFER_SIZE)
      {
        SDL_RWseek(file, -20, RW_SEEK_CUR);
        continue; /* re-scan this place */
      }

      if(SDL_memcmp(head, "\xFF\xE1", 2) == 0) /* EXIF, skip it!*/
      {
        const Sint64 curPos = pos + (head - raw);
        Sint64 toSkip = BE16(head, 2); //-V629
        SDL_RWseek(file, curPos + toSkip + 2, RW_SEEK_SET);
        continue;
      }

      *h = BE16(head, 5);
      *w = BE16(head, 7);
      return true;
    }
  } while(chunk_size > 0);               // <=

  return false;
}

Snort

V654 The condition '!done' of loop is always true. log.c 207

void PrintNetData(....)
{
  int done;           /* flag */
  ....

  /* initialization */
  done = 0;
  ....

  /* loop thru the whole buffer */
  while(!done)
    {
      ....
    }
  ....
}

Free Heroes of Might and Magic II

V654 The condition 'i < originalPalette.size()' of loop is always false. battle_interface.cpp 3689

void Battle::Interface::RedrawActionBloodLustSpell( Unit & target )
{
  std::vector<std::vector<uint8_t> > originalPalette;
  if ( target.Modes( SP_STONE ) )
  {
    originalPalette.push_back( PAL::GetPalette( PAL::GRAY ) );
  }
  else if ( target.Modes( CAP_MIRRORIMAGE ) )
  {
    originalPalette.push_back( PAL::GetPalette( PAL::MIRROR_IMAGE ) );
  }
  if ( !originalPalette.empty() )
  {
    for ( size_t i = 1; i < originalPalette.size(); ++i )
    {
      originalPalette[0] = PAL::CombinePalettes( originalPalette[0],
                                                 originalPalette[i] );
    }
    fheroes2::ApplyPalette( unitSprite, originalPalette[0] );
  }
  ....
}

Newton Game Dynamics

V654 The condition 'i < count' of loop is always false. MultiBodyCar.cpp 942

void MultibodyBodyCar(DemoEntityManager* const scene)
{
  ....
  int count = 10;
  count = 0;
  for (int i = 0; i < count; i++)
  {
    for (int j = 0; j < count; j++)
    {
      dMatrix offset(location);
      offset.m_posit += dVector (j * 5.0f + 4.0f, 0.0f, i * 5.0f, 0.0f);
      //manager->CreateSportCar(offset, viperModel.GetData());
      manager->CreateOffRoadCar(offset, monsterTruck.GetData());
    }
  }
  ....
}

Doom 1

V654 [CWE-834] The condition 'player->pendingweapon == wp_nochange' of loop is always false. p_pspr.c 232

boolean P_CheckAmmo (player_t* player)
{
  ....
  do {
    if (....)
    {
      player->pendingweapon = wp_plasma;
    }
    else .... if (....)
    {
      player->pendingweapon = wp_bfg;
    }
    else
    {
      player->pendingweapon = wp_fist;
    }
  } while (player->pendingweapon == wp_nochange);
  ....
}

Haiku Operation System

V654 The condition 'specificSequence != sequence' of loop is always false. pthread_key.cpp 55

static void*
get_key_value(pthread_thread* thread, uint32 key, int32 sequence)
{
  pthread_key_data& keyData = thread->specific[key];
  int32 specificSequence;
  void* value;

  do {
    specificSequence = keyData.sequence;
    if (specificSequence != sequence)
      return NULL;

    value = keyData.value;
  } while (specificSequence != sequence);

  keyData.value = NULL;

  return value;
}

Stellarium

V654 The condition 'start_of_directory == - 1' of loop is always true. qzip.cpp 617

void QZipReaderPrivate::scanFiles()
{
  ....
  // find EndOfDirectory header
  int i = 0;
  int start_of_directory = -1;
  EndOfDirectory eod;
  while (start_of_directory == -1) {
    const int pos = device->size()
      - int(sizeof(EndOfDirectory)) - i;
    if (pos < 0 || i > 65535) {
      qWarning() << "QZip: EndOfDirectory not found";
      return;
    }

    device->seek(pos);
    device->read((char *)&eod, sizeof(EndOfDirectory));
    if (readUInt(eod.signature) == 0x06054b50)
      break;
    ++i;
  }
  ....
}

Android

V654 CWE-834 The condition '++ retries' of loop is always true. SimpleDecodingSource.cpp 226

status_t SimpleDecodingSource::doRead(....) {
  ....
  for (int retries = 0; ++retries; ) {
  ....
}

Android

V654 CWE-834 The condition 'gate_id <= 0xFF' of loop is always true. nfa_hci_utils.cc 248

#define NFA_HCI_LAST_PROP_GATE 0xFF

tNFA_HCI_DYN_GATE* nfa_hciu_alloc_gate(uint8_t gate_id,
                                       tNFA_HANDLE app_handle) {
  ....
  for (gate_id = NFA_HCI_FIRST_HOST_SPECIFIC_GENERIC_GATE;
       gate_id <= NFA_HCI_LAST_PROP_GATE; gate_id++) {
    if (gate_id == NFA_HCI_CONNECTIVITY_GATE) gate_id++;
    if (nfa_hciu_find_gate_by_gid(gate_id) == NULL) break;
  }

  if (gate_id > NFA_HCI_LAST_PROP_GATE) {
    LOG(ERROR) << StringPrintf(
        "nfa_hci_alloc_gate - no free Gate ID: %u  "
        "App Handle: 0x%04x", gate_id, app_handle);
    return (NULL);
  }
  ....
}

RT-Thread

V654 CWE-834 The condition 'i <= 255' of loop is always true. drv_ft5x06.c 160

static int ft5x06_dump(void)
{
  uint8_t i;
  uint8_t reg_value;

  DEBUG_PRINTF("[FTS] Touch Chip\r\n");

  for (i = 0; i <= 255; i++)
  {
    _ft5x06_read(i, ®_value, 1);

    if (i % 8 == 7)
      DEBUG_PRINTF("0x%02X = 0x%02X\r\n", i, reg_value);
    else
      DEBUG_PRINTF("0x%02X = 0x%02X ", i, reg_value);
  }
  DEBUG_PRINTF("\n");

  return 0;
}

Ardour

V654 The condition 'tries < 8' of loop is always true. session_transport.cc 68

void
Session::add_post_transport_work (PostTransportWork ptw)
{
  PostTransportWork oldval;
  PostTransportWork newval;
  int tries = 0;

  while (tries < 8) {
    oldval = (PostTransportWork) g_atomic_int_get (....);
    newval = PostTransportWork (oldval | ptw);
    if (g_atomic_int_compare_and_exchange (....)) {
      /* success */
      return;
    }
  }

  error << "Could not set post transport work! ...." << endmsg;
}

EFL Core Libraries

V654 The condition of loop is always false. evas_font_query.c 376

EAPI void
evas_common_font_query_size(....)
{
  ....
  size_t cluster = 0;
  size_t cur_cluster = 0;
  ....
  do
  {
    cur_cluster = cluster + 1;

    glyph--;
    if (cur_w > ret_w)
    {
      ret_w = cur_w;
    }
  }
  while ((glyph > first_glyph) && (cur_cluster == cluster));
  ....
}

Unreal Engine 4

V654 The condition '!bFoundName' of loop is always true. edgraphutilities.cpp 244

void FEdGraphUtilities::RenameGraphCloseToName(....)
{
  bool bFoundName = false;

  FString NewName = BaseName;

  int32 NameIndex = StartIndex;
  while (!bFoundName)
  {
    if (Graph->Rename(*NewName, Graph->GetOuter(), REN_Test))
    {
      UBlueprint* BP = FBlueprintEditorUtils....;
      Graph->Rename(*NewName, Graph->GetOuter(), ....);
      return;
    }

    NewName = FString::Printf(TEXT("%s_%d"),*BaseName,NameIndex);
    ++NameIndex;
  }
}

Linux Kernel

V654 The condition 'i < 10' of loop is always true. qla3xxx.c 149

static int ql_wait_for_drvr_lock(struct ql3_adapter *qdev)
{
  int i = 0;

  while (i < 10) {
    if (i)
      ssleep(1);

    if (ql_sem_lock(qdev,
        QL_DRVR_SEM_MASK,
        (QL_RESOURCE_BITS_BASE_CODE | (qdev->mac_index)
         * 2) << 1)) {
      netdev_printk(KERN_DEBUG, qdev->ndev,
              "driver lock acquired\n");
      return 1;
    }
  }

  netdev_err(qdev->ndev,
             "Timed out waiting for driver lock...\n");
  return 0;
}

Miranda NG

V654 The condition '5' of loop is always true. Xfire main.cpp 1110

extern "C" __declspec(dllexport) int  Load(void)
{
  ....
  for (i = MAX_PATH; 5; i--){
  ....
}

Similar errors can be found in some other places:

• V654 The condition '5' of loop is always true. Xfire variables.cpp 194

K Desktop Environment

V654 The condition 'state != 1' of loop is always true. passwd.cpp 255

int PasswdProcess::ConversePasswd(....)
{
  ....
  state = 0;
  while (state != 1)
  {
    line = readLine();
    if (line.isNull())
    {
      // No more input... OK
      return 0;
    }
    if (isPrompt(line, "password"))
    {
      // Uh oh, another prompt. Not good!
      kill(m_Pid, SIGKILL);
      waitForChild();
      return PasswordNotGood;
    }
    m_Error += line + '\n'; // Collect error message
  }
  ....
}

Oracle VM Virtual Box

V654 The condition of loop is always true. suphardenedverifyprocess-win.cpp 1732

DECLHIDDEN(int) supHardNtLdrCacheOpen(const char *pszName, ....)
{
  ....
  uint32_t i = 0;
  while (i < RT_ELEMENTS(g_apszSupNtVpAllowedDlls))
    if (!strcmp(pszName, g_apszSupNtVpAllowedDlls[i]))
      break;
  ....
}

What is dangerous about this loop is that the counter value doesn't change, so if the very first array item doesn't coincide with 'pszName', we'll get an infinite loop.

WebRTC

V654 The condition 'loopCnt < 5' of loop is always true. cpr_win_socket.c 746

#define TCP_PORT_RETRY_CNT  5

cpr_socket_t
cprSecSocConnect (char *host,
                  int     port,
                  int     ipMode,
                  boolean mode,
                  uint32_t tos,
                  uint16_t *localPort)
{
  ....
  uint16_t loopCnt  = 0;
  ....
  while (loopCnt < TCP_PORT_RETRY_CNT) {
    ....
    .... // loopCnt not changed
    ....
  }
  ....
}

Apache HTTP Server

V654 The condition 'retry < 2' of loop is always true. mod_proxy_wstunnel mod_proxy_wstunnel.c 436

static int proxy_wstunnel_handler(....)
{
  int retry;
  ....
  retry = 0;
  while (retry < 2) {
    char *locurl = url;
    ....
    // Variable 'retry' is not used
    ....
  }
  ....
}