archive_read_format_rar_read_data(struct archive_read *a, const void **buff,
                                  size_t *size, int64_t *offset)
{
  struct rar *rar = (struct rar *)(a->format->data);
  int ret;

  if (rar->has_encrypted_entries == ARCHIVE_READ_FORMAT_ENCRYPTION_DONT_KNOW) {
	  rar->has_encrypted_entries = 0;
  }

  if (rar->bytes_unconsumed > 0) {
      /* Consume as much as the decompressor actually used. */
      __archive_read_consume(a, rar->bytes_unconsumed);
      rar->bytes_unconsumed = 0;
  }

  *buff = NULL;
  if (rar->entry_eof || rar->offset_seek >= rar->unp_size) {
    *size = 0;
    *offset = rar->offset;
    if (*offset < rar->unp_size)
      *offset = rar->unp_size;
    return (ARCHIVE_EOF);
  }

  switch (rar->compression_method)
  {
  case COMPRESS_METHOD_STORE:
    ret = read_data_stored(a, buff, size, offset);
    break;

  case COMPRESS_METHOD_FASTEST:
  case COMPRESS_METHOD_FAST:
  case COMPRESS_METHOD_NORMAL:
  case COMPRESS_METHOD_GOOD:
  case COMPRESS_METHOD_BEST:
    ret = read_data_compressed(a, buff, size, offset);
    if (ret != ARCHIVE_OK && ret != ARCHIVE_WARN)
      __archive_ppmd7_functions.Ppmd7_Free(&rar->ppmd7_context, &g_szalloc);
    break;

  default:
    archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,
                      "Unsupported compression method for RAR file.");
    ret = ARCHIVE_FATAL;
    break;
  }
  return (ret);
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.