nullptr derefence in the source .\tgl-master\queries.c

[ghsrcgh]

Details of the nullptr dereference is written in that ticket: majn/telegram-purple#431

I will copy most important part from comment:

nullptr derefence in the source .\tgl-master\queries.c (my comments are started with "//"):

int tglq_query_error (struct tgl_state *TLS, long long id) {
  assert (fetch_int () == CODE_rpc_error);
  int error_code = fetch_int ();
  int error_len = prefetch_strlen ();
  char *error = fetch_str (error_len);

  struct query *q = tglq_query_get (TLS, id);
  // (q == nullptr)?
  if (!q)
  {
      vlogprintf (E_WARNING, "error for query '%s' #%" INT64_PRINTF_MODIFIER "d: #%d :%.*s\n", q->methods->name, id, error_code, error_len, error);
      // q == nullptr and you are trying to dereferencing null pointer?! q->methods ... ?! WTF??!
      // it is crashing here with an access violation (C.O.)
      vlogprintf (E_WARNING, "No such query\n");
  }
  else
  {

You cannot defererence q->methods here, because q is nullptr! It is a bug in source.

[BenWiederhake]

Awesome, thanks! Our fork of this library already contains the fix in commit ac2e73b since February, and in dev-1.4.0 at least since June.

If you were experiencing crashes with telegram-purple, I strongly recommend upgrading to the intermediate branch dev-1.4.0. (Don't forget git submodule sync && git submodule update!)