ActivateImplicitGrab(DeviceIntPtr dev, ClientPtr client, WindowPtr win,
                     xEvent *event, Mask deliveryMask)
{
    GrabPtr tempGrab;
    OtherInputMasks *inputMasks;
    CARD8 type = event->u.u.type;
    enum InputLevel grabtype;

    if (type == ButtonPress)
        grabtype = CORE;
    else if (type == DeviceButtonPress)
        grabtype = XI;
    else if ((type = xi2_get_type(event)) == XI_ButtonPress)
        grabtype = XI2;
    else
        return FALSE;

    tempGrab = AllocGrab(NULL);
    if (!tempGrab)
        return FALSE;
    tempGrab->next = NULL;
    tempGrab->device = dev;
    tempGrab->resource = client->clientAsMask;
    tempGrab->window = win;
    tempGrab->ownerEvents = (deliveryMask & OwnerGrabButtonMask) ? TRUE : FALSE;
    tempGrab->eventMask = deliveryMask;
    tempGrab->keyboardMode = GrabModeAsync;
    tempGrab->pointerMode = GrabModeAsync;
    tempGrab->confineTo = NullWindow;
    tempGrab->cursor = NullCursor;
    tempGrab->type = type;
    tempGrab->grabtype = grabtype;

    /* get the XI and XI2 device mask */
    inputMasks = wOtherInputMasks(win);
    tempGrab->deviceMask = (inputMasks) ? inputMasks->inputEvents[dev->id] : 0;

    if (inputMasks)
        xi2mask_merge(tempGrab->xi2mask, inputMasks->xi2mask);

    (*dev->deviceGrab.ActivateGrab) (dev, tempGrab,
                                     currentTime, TRUE | ImplicitGrabMask);
    FreeGrab(tempGrab);
    return TRUE;
}

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.