png_convert_to_rfc1123(png_structp png_ptr, png_timep ptime)
{
   static PNG_CONST char short_months[12][4] =
        {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
         "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
 
    if (png_ptr == NULL)
       return (NULL);

    if (png_ptr->time_buffer == NULL)
    {
       png_ptr->time_buffer = (png_charp)png_malloc(png_ptr, (png_uint_32)(29*
         png_sizeof(char)));
   }

#ifdef _WIN32_WCE
    {
       wchar_t time_buf[29];
       wsprintf(time_buf, TEXT("%d %S %d %02d:%02d:%02d +0000"),
          ptime->day % 32, short_months[(ptime->month - 1U) % 12],
         ptime->year, ptime->hour % 24, ptime->minute % 60,
           ptime->second % 61);
       WideCharToMultiByte(CP_ACP, 0, time_buf, -1, png_ptr->time_buffer,
          29, NULL, NULL);
   }
#else
#ifdef USE_FAR_KEYWORD
    {
       char near_time_buf[29];
       png_snprintf6(near_time_buf, 29, "%d %s %d %02d:%02d:%02d +0000",
          ptime->day % 32, short_months[(ptime->month - 1U) % 12],
           ptime->year, ptime->hour % 24, ptime->minute % 60,
           ptime->second % 61);
       png_memcpy(png_ptr->time_buffer, near_time_buf,
           29*png_sizeof(char));
    }
 #else
    png_snprintf6(png_ptr->time_buffer, 29, "%d %s %d %02d:%02d:%02d +0000",
       ptime->day % 32, short_months[(ptime->month - 1U) % 12],
        ptime->year, ptime->hour % 24, ptime->minute % 60,
        ptime->second % 61);
 #endif
#endif /* _WIN32_WCE */
   return ((png_charp)png_ptr->time_buffer);
}

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.