CheckVirtualMotion(DeviceIntPtr pDev, QdEventPtr qe, WindowPtr pWin)
{
    SpritePtr pSprite = pDev->spriteInfo->sprite;
    RegionPtr reg = NULL;
    DeviceEvent *ev = NULL;

    if (qe) {
        ev = &qe->event->device_event;
        switch (ev->type) {
        case ET_Motion:
        case ET_ButtonPress:
        case ET_ButtonRelease:
        case ET_KeyPress:
        case ET_KeyRelease:
        case ET_ProximityIn:
        case ET_ProximityOut:
            pSprite->hot.pScreen = qe->pScreen;
            pSprite->hot.x = ev->root_x;
            pSprite->hot.y = ev->root_y;
            pWin =
                pDev->deviceGrab.grab ? pDev->deviceGrab.grab->
                confineTo : NullWindow;
            break;
        default:
            break;
        }
    }
    if (pWin) {
        BoxRec lims;

#ifdef PANORAMIX
        if (!noPanoramiXExtension) {
            int x, y, off_x, off_y, i;

            if (!XineramaSetWindowPntrs(pDev, pWin))
                return;

            i = PanoramiXNumScreens - 1;

            RegionCopy(&pSprite->Reg2, &pSprite->windows[i]->borderSize);
            off_x = screenInfo.screens[i]->x;
            off_y = screenInfo.screens[i]->y;

            while (i--) {
                x = off_x - screenInfo.screens[i]->x;
                y = off_y - screenInfo.screens[i]->y;

                if (x || y)
                    RegionTranslate(&pSprite->Reg2, x, y);

                RegionUnion(&pSprite->Reg2, &pSprite->Reg2,
                            &pSprite->windows[i]->borderSize);

                off_x = screenInfo.screens[i]->x;
                off_y = screenInfo.screens[i]->y;
            }
        }
        else
#endif
        {
            if (pSprite->hot.pScreen != pWin->drawable.pScreen) {
                pSprite->hot.pScreen = pWin->drawable.pScreen;
                pSprite->hot.x = pSprite->hot.y = 0;
            }
        }

        lims = *RegionExtents(&pWin->borderSize);
        if (pSprite->hot.x < lims.x1)
            pSprite->hot.x = lims.x1;
        else if (pSprite->hot.x >= lims.x2)
            pSprite->hot.x = lims.x2 - 1;
        if (pSprite->hot.y < lims.y1)
            pSprite->hot.y = lims.y1;
        else if (pSprite->hot.y >= lims.y2)
            pSprite->hot.y = lims.y2 - 1;

#ifdef PANORAMIX
        if (!noPanoramiXExtension) {
            if (RegionNumRects(&pSprite->Reg2) > 1)
                reg = &pSprite->Reg2;

        }
        else
#endif
        {
            if (wBoundingShape(pWin))
                reg = &pWin->borderSize;
        }

        if (reg)
            ConfineToShape(pDev, reg, &pSprite->hot.x, &pSprite->hot.y);

        if (qe && ev) {
            qe->pScreen = pSprite->hot.pScreen;
            ev->root_x = pSprite->hot.x;
            ev->root_y = pSprite->hot.y;
        }
    }
#ifdef PANORAMIX
    if (noPanoramiXExtension)   /* No typo. Only set the root win if disabled */
#endif
        RootWindow(pDev->spriteInfo->sprite) = pSprite->hot.pScreen->root;
}

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.