Here is a list of some unchecked return values in 6.9.0 apps (not fixed in 7.4). Though they might not be exposed dynamically, they are defects nevertheless. Could these be fixed?

V: ./xc/programs/x11perf/x11perf.c:884:    doit = (Bool *)calloc(numTests, sizeof(Bool));
V: ./xc/programs/setxkbmap/setxkbmap.c:563:	orig= (char *)calloc(len,1);
V: ./xc/programs/twm/add_window.c:1555:	  (char *) calloc(1, ColormapsScoreboardLength(&tmp->cmaps));
V: ./xc/programs/xterm/main.c:2239:	    (void) fcntl(i, F_SETFD, 1);
V: ./xc/programs/xterm/main.c:4147:		fcntl(cp_pipe[1], F_SETFD, 1);
V: ./xc/programs/xterm/main.c:4148:		fcntl(pc_pipe[0], F_SETFD, 1);
V: ./xc/programs/xterm/os2main.c:1268:	    (void) fcntl(i, F_SETFD, 1);
V: ./xc/programs/luit/luit.c:558:        fcntl(0, F_SETFL, val | O_NONBLOCK);
V: ./xc/programs/luit/luit.c:562:        fcntl(pty, F_SETFL, val | O_NONBLOCK);
V: ./xc/programs/proxymngr/main.c:89:    (void) fcntl (fd, F_SETFD, FD_CLOEXEC);
V: ./xc/programs/proxymngr/main.c:91:    (void) fcntl (fd, F_SETFD, 1);
V: ./xc/programs/bitmap/bmtoa.c:91:    fp = fopen (tmpfilename, "w");
V: ./xc/programs/xditview/Dvi.c:465:	dw->dvi.tmpFile = fopen (tmpName, "w+");
V: ./xc/programs/xmh/miscfuncs.c:80:    (void) fstat(fd, &stat_val);
V: ./xc/programs/xterm/main.c:3920:			pw = getpwuid(screen->uid);
V: ./xc/programs/xterm/main.c:3924:			pw = getpwuid(screen->uid);
V: ./xc/programs/xpr/xpr.c:1481:    pswd = getpwuid (getuid ());
V: ./xc/programs/xev/xev.c:107:      buf = malloc (bsize);
V: ./xc/programs/twm/iconmgr.c:140:    p = (IconMgr *)malloc(sizeof(IconMgr));
V: ./xc/programs/twm/iconmgr.c:375:    tmp = (WList *) malloc(sizeof(WList));
V: ./xc/programs/twm/parse.c:994:    chead = (Cptr)malloc(sizeof(Cnode));
V: ./xc/programs/twm/parse.c:1000:    cpnew = (Cptr)malloc(sizeof(Cnode));
V: ./xc/programs/twm/menus.c:196:	tmp = (FuncKey *) malloc(sizeof(FuncKey));
V: ./xc/programs/twm/menus.c:620:    tmp = (MenuRoot *) malloc(sizeof(MenuRoot));
V: ./xc/programs/twm/menus.c:684:    tmp = (MenuItem *) malloc(sizeof(MenuItem));
V: ./xc/programs/twm/menus.c:987:              (TwmWindow **)malloc(sizeof(TwmWindow *)*WindowNameCount);
V: ./xc/programs/twm/add_window.c:1539:	cwins = (ColormapWindow **) malloc(sizeof(ColormapWindow *));
V: ./xc/programs/twm/session.c:748:	char *ptr = (char *) malloc (strlen (tmp) + 1);
V: ./xc/programs/twm/twm.c:478:		(ColormapWindow **) malloc(sizeof(ColormapWindow *));
V: ./xc/programs/twm/icons.c:64:	    new = (IconEntry *)malloc (sizeof (IconEntry));
V: ./xc/programs/twm/icons.c:85:	    new = (IconEntry *)malloc (sizeof (IconEntry));
V: ./xc/programs/twm/icons.c:272:    ir = (IconRegion *)malloc(sizeof(IconRegion));
V: ./xc/programs/twm/icons.c:298:    ir->entries = (IconEntry *)malloc(sizeof(IconEntry));
V: ./xc/programs/xrdb/xrdb.c:329:	temp = (char *)malloc(length + 1);
V: ./xc/programs/xrdb/xrdb.c:339:	temp = (char *)malloc(length + 1);
V: ./xc/programs/xrdb/xrdb.c:999:	dbs = (Entries *)malloc(ScreenCount(dpy) * sizeof(Entries));
V: ./xc/programs/xrdb/xrdb.c:1276:    hits = (int *)malloc(num * sizeof(int));
V: ./xc/programs/x11perf/x11perf.c:873:    saveargv = (char **) malloc(argc * sizeof(char *));
V: ./xc/programs/x11perf/do_text.c:79:    charBuf = (char **) malloc(totalLines*sizeof (char *));
V: ./xc/programs/x11perf/do_text.c:81:	items = (XTextItem *) malloc(totalLines*SEGS*sizeof (XTextItem));
V: ./xc/programs/x11perf/do_text.c:84:	charBuf[i] = (char *) malloc (sizeof (char)*charsPerLine);
V: ./xc/programs/x11perf/do_text.c:176:	items = (XTextItem *) malloc(totalLines*SEGS*sizeof (XTextItem));
V: ./xc/programs/x11perf/do_text.c:180:			    (char *) malloc (sizeof (char)*charsPerLine/2);
V: ./xc/programs/x11perf/do_text.c:185:			    (char *) malloc (sizeof (char)*charsPerLine);
V: ./xc/programs/x11perf/do_text.c:190:			    (char *) malloc (sizeof (char)*charsPerLine/2);
V: ./xc/programs/x11perf/do_text.c:209:	charBuf = (char **) malloc(totalLines*sizeof (char *));
V: ./xc/programs/x11perf/do_text.c:211:	    pbuf0 = charBuf[i] = (char *) malloc (sizeof (char)*charsPerLine*2);
V: ./xc/programs/x11perf/do_text.c:462:    charBuf = (char **) malloc(totalLines*sizeof (char *));
V: ./xc/programs/x11perf/do_text.c:465:	charBuf[i] = (char *) malloc (sizeof (char)*charsPerLine);
V: ./xc/programs/x11perf/do_arcs.c:51:    arcs = (XArc *)malloc((p->objects) * sizeof(XArc));
V: ./xc/programs/x11perf/do_arcs.c:257:    arcs = (XArc *)malloc((p->objects) * sizeof(XArc));
V: ./xc/programs/x11perf/do_rects.c:53:    rects = (XRectangle *)malloc(p->objects * sizeof(XRectangle));
V: ./xc/programs/x11perf/do_segs.c:55:    segments = (XSegment *)malloc((p->objects) * sizeof(XSegment));
V: ./xc/programs/x11perf/do_segs.c:230:    segments = (XSegment *)malloc((p->objects) * sizeof(XSegment));
V: ./xc/programs/x11perf/do_segs.c:303:    segments = (XSegment *)malloc((p->objects) * sizeof(XSegment));
V: ./xc/programs/x11perf/do_tris.c:93:    points = (XPoint *)malloc(numPoints * sizeof(XPoint));
V: ./xc/programs/x11perf/do_movewin.c:49:    children = (Window *) malloc (p->objects*sizeof (Window));
V: ./xc/programs/x11perf/do_movewin.c:50:    positions = (XPoint *) malloc(p->objects*sizeof(XPoint));
V: ./xc/programs/x11perf/do_movewin.c:118:    children = (Window *) malloc (p->objects * sizeof (Window));
V: ./xc/programs/x11perf/do_movewin.c:162:    children = (Window *) malloc (p->objects*sizeof (Window));
V: ./xc/programs/x11perf/do_movewin.c:163:    positions = (XPoint *) malloc(p->objects*sizeof(XPoint));
V: ./xc/programs/x11perf/do_traps.c:46:    points = (XPoint *)malloc(numPoints * sizeof(XPoint));
V: ./xc/programs/x11perf/do_traps.c:144:    traps = (XTrap *)malloc(numTraps * sizeof(XTrap));
V: ./xc/programs/x11perf/do_traps.c:282:    trapezoids = (XTrapezoid *)malloc(numTraps * sizeof(XTrapezoid));
V: ./xc/programs/x11perf/do_complex.c:72:    points = (XPoint *)malloc(numPoints * sizeof(XPoint));
V: ./xc/programs/x11perf/do_complex.c:147:    points = (XPoint *) malloc (numPoints * sizeof (XPoint));
V: ./xc/programs/x11perf/do_blt.c:151:    segsa = (XSegment *)malloc(reps * sizeof(XSegment));
V: ./xc/programs/x11perf/do_blt.c:152:    segsb = (XSegment *)malloc(reps * sizeof(XSegment));
V: ./xc/programs/x11perf/do_dots.c:38:    points = (XPoint *)malloc(p->objects * sizeof(XPoint));
V: ./xc/programs/x11perf/do_windows.c:64:    isolates = (Window *)malloc(parentwindows * sizeof(Window));
V: ./xc/programs/x11perf/do_windows.c:65:    parents = (Window *)malloc(parentwindows * sizeof(Window));
V: ./xc/programs/x11perf/do_lines.c:56:    points = (XPoint *)malloc((p->objects+1) * sizeof(XPoint));
V: ./xc/programs/smproxy/smproxy.c:242:	    newptr = (char *) malloc (bytes);
V: ./xc/programs/smproxy/save.c:358:	char *ptr = (char *) malloc (strlen (tmp) + 1);
V: ./xc/programs/xgc/planemask.c:81:  pm = (Widget *) malloc(num_planes * sizeof(Widget));
V: ./xc/programs/xgc/planemask.c:82:  pminfo = (int *) malloc(num_planes * sizeof(int));
V: ./xc/programs/xgc/dashlist.c:73:  dashes = (Widget *) malloc(DASHLENGTH * sizeof(Widget));
V: ./xc/programs/xgc/dashlist.c:74:  dashinfo = (int *) malloc(DASHLENGTH * sizeof(int));
V: ./xc/programs/xgc/tests.c:180:  coord = (XPoint *) malloc (sizeof(XPoint)*(num_vertices+1));
V: ./xc/programs/xgc/tests.c:222:  segments = (XSegment *) malloc(sizeof(XSegment) * num_segments);
V: ./xc/programs/xgc/tests.c:258:  points = (XPoint *) malloc(sizeof(XPoint) * num_points);
V: ./xc/programs/xgc/tests.c:293:  rects = (XRectangle *) malloc(sizeof(XRectangle) * num_rects);
V: ./xc/programs/xgc/tests.c:342:  points = (XPoint *) malloc (sizeof(XPoint) * points_per_side * 4);
V: ./xc/programs/xgc/tests.c:387:  arcs = (XArc *) malloc(sizeof(XArc) * num_arcs);
V: ./xc/programs/proxymngr/pmdb.c:738:		server = (server_list *) malloc (sizeof (server_list));
V: ./xc/programs/proxymngr/main.c:183:    p = (char *) malloc(sizeof ("PROXY_MANAGER") + strlen(networkIds) + 2);
V: ./xc/programs/proxymngr/main.c:473:	    authData = (char *) malloc (authLen);
V: ./xc/programs/xman/man.c:530:    s1 = (char **)malloc(man->nentries * sizeof(char *));
V: ./xc/programs/rstart/server.c:189:    cs = malloc(strlen(s)+1);
V:  ./xc/programs/xkbutils/utils.c:40:    return((Opaque)malloc(size));
V:  ./xc/programs/xkbutils/utils.c:61:	 return((Opaque)malloc(newSize));
V: ./xc/programs/xpr/x2pmp.c:119:	XColor *colors = (XColor *)malloc((unsigned) (header.ncolors * sizeof(XColor)));
V: ./xc/programs/xpr/xpr.c:375:    w_name = malloc((unsigned)(win.header_size - sizeof win));
V: ./xc/programs/xpr/xpr.c:380:	colors = (XColor *)malloc((unsigned) (win.ncolors * sizeof(XColor)));
V: ./xc/programs/xpr/xpr.c:406:    data = malloc((unsigned)size);
V: ./xc/programs/xpr/xpr.c:434:	sixmap = (unsigned char (*)[])malloc((unsigned)sixel_count);
V: ./xc/programs/xpr/xpr.c:1100:	    ffbuf = (unsigned char *)malloc((unsigned)iwb);
V:  ./xc/programs/xpr/xpr.c:1622:    bp = (unsigned char *)malloc((unsigned)(iw*ih+512));
V: ./xc/programs/xpr/xpr.c:1696:    bp = (unsigned char *)malloc((unsigned)(iw*ih+512));
V: ./xc/programs/xpr/xpr.c:1788:	ibuf = (unsigned char *)malloc((unsigned)(iwb + 3));
V: ./xc/programs/luit/sys.c:397:    line = malloc(strlen(name) + 1);
V: ./xc/programs/bitmap/atobm.c:89:  result = (char *) malloc (length + 1);
V: ./xc/programs/xmodmap/handle.c:67:		    kcs = (KeyCode *)malloc(sizeof(KeyCode));
V: ./xc/programs/xmodmap/handle.c:89:	buf = (char *) malloc (buflen+1);
V: ./xc/programs/xfwp/pm.c:162:        authData = (char *) malloc (authLen);
V: ./xc/programs/xfwp/pm.c:273:	      tmpAddress = (char *) malloc (strlen (hostent->h_name) + 
V: ./xc/programs/xwud/xwud.c:364:	map_name = malloc(strlen(std) + 9);
V: ./xc/programs/xwud/xwud.c:379:	vt = malloc(strlen(vis) + 1);
V: ./xc/programs/xwud/xwud.c:774:    dest_image->data = malloc(dest_image->bytes_per_line * h);
V: ./xc/programs/xwud/xwud.c:778:    table.x = (Position *) malloc(sizeof(Position) * (src_image->width + 1));
V: ./xc/programs/xwud/xwud.c:779:    table.y = (Position *) malloc(sizeof(Position) * (src_image->height + 1));
V: ./xc/programs/xwud/xwud.c:780:    table.width = (Dimension *) malloc(sizeof(Dimension) * src_image->width);
V: ./xc/programs/xwud/xwud.c:781:    table.height = (Dimension *) malloc(sizeof(Dimension)*src_image->height);
V: ./xc/programs/xwud/xwud.c:1025:	pixels = (unsigned long *)malloc(sizeof(unsigned long) * pix);
V: ./xc/programs/xwud/xwud.c:1090:	pixels = (unsigned long *)malloc(sizeof(unsigned long) * pix);
V: ./xc/programs/xwud/xwud.c:1091:	rpixels = (unsigned long *)malloc(sizeof(unsigned long) * pix);
V: ./xc/programs/xauth/process.c:1560:	key = malloc(len-1);
V: ./xc/programs/xauth/process.c:1565:	key = malloc(len+1);
V: ./xc/programs/xauth/process.c:1863:		authdata = malloc(authdatalen-1);
V: ./xc/programs/xterm/main.c:3879:	    close(open(ttydev, O_WRONLY));
V: ./xc/programs/xmh/miscfuncs.c:55:    new_fid = open(tmp_file, O_RDWR | O_CREAT);
V: ./xc/programs/rstart/server.c:739:		dup(dup(open("/dev/null", O_RDWR)));
V: ./xc/programs/xrdb/xrdb.c:182:	b->buff = (char *)realloc(b->buff, 2*b->room*(sizeof(char)));
V: ./xc/programs/xrdb/xrdb.c:234:	e->entry = (Entry *)realloc((char *)e->entry,
V: ./xc/programs/setxkbmap/setxkbmap.c:559:	orig= (char *)realloc(orig,len);
V: ./xc/programs/xev/xev.c:119:                buf = realloc (buf, bsize);
V: ./xc/programs/xmodmap/handle.c:69:		    kcs = (KeyCode *)realloc((char *)kcs,
V: ./xc/programs/proxymngr/main.c:539:			serverAddress = (char *) realloc (serverAddress, len);
V: ./xc/programs/ico/ico.c:304:	select(1,NULL,NULL,NULL,&timeout);
V: ./xc/programs/xterm/misc.c:2689:    select(0, 0, 0, 0, &select_timeout);
V: ./xc/programs/xf86dga/dga.c:144:   setuid(getuid());
V: ./xc/programs/xinit/xinit.c:695:		setuid(getuid());
V: ./xc/programs/xload/xload.c:166:    setuid(getuid());
V: ./xc/programs/xterm/main.c:1596:    setuid(getuid());
V: ./xc/programs/xterm/main.c:1623:    setuid(getuid());
V: ./xc/programs/xterm/main.c:2970:	setuid(screen->uid);
V: ./xc/programs/xterm/os2main.c:1569:	setuid(screen->uid);
V: ./xc/programs/xterm/os2main.c:1825:	    setuid(screen->uid);
V: ./xc/programs/xterm/print.c:392:	    setuid(screen->uid);
V: ./xc/programs/xterm/misc.c:1098:	setuid(uid);
V: ./xc/programs/xterm/misc.c:1266:	    setuid(screen->uid);
V: ./xc/programs/xstdcmap/xstdcmap.c:280:    vinfo = XGetVisualInfo(dpy, VisualScreenMask, &template, &nvisuals);
V: ./xc/programs/xrdb/xrdb.c:573:    vinfos = XGetVisualInfo(display, VisualScreenMask, &vinfo, &nv);
V: ./xc/programs/glxinfo/glxinfo.c:675:   visuals = XGetVisualInfo(dpy, mask, &theTemplate, &numVisuals);
V: ./xc/programs/xclipboard/xcutsel.c:283:    box = XtCreateManagedWidget("box", boxWidgetClass, shell, NULL, ZERO);
V: ./xc/programs/xclipboard/xcutsel.c:286:	XtCreateManagedWidget("quit", commandWidgetClass, box, NULL, ZERO);
V: ./xc/programs/xclipboard/xcutsel.c:296:	XtCreateManagedWidget("sel-cut", commandWidgetClass, box, NULL, ZERO);
V: ./xc/programs/xclipboard/xcutsel.c:305:	XtCreateManagedWidget("cut-sel", commandWidgetClass, box, NULL, ZERO);
V: ./xc/programs/xclipboard/xclipboard.c:626:    parent = XtCreateManagedWidget("form", formWidgetClass, top, NULL, ZERO);
V: ./xc/programs/xclipboard/xclipboard.c:627:    (void) XtCreateManagedWidget("quit", Command, parent, NULL, ZERO);
V: ./xc/programs/xclipboard/xclipboard.c:628:    (void) XtCreateManagedWidget("delete", Command, parent, NULL, ZERO);
V: ./xc/programs/xclipboard/xclipboard.c:629:    (void) XtCreateManagedWidget("new", Command, parent, NULL, ZERO);
V: ./xc/programs/xclipboard/xclipboard.c:630:    (void) XtCreateManagedWidget("save", Command, parent, NULL, ZERO);
V: ./xc/programs/xclipboard/xclipboard.c:631:    nextButton = XtCreateManagedWidget("next", Command, parent, NULL, ZERO);
V: ./xc/programs/xclipboard/xclipboard.c:632:    prevButton = XtCreateManagedWidget("prev", Command, parent, NULL, ZERO);
V: ./xc/programs/xclipboard/xclipboard.c:633:    indexLabel = XtCreateManagedWidget("index", Label, parent, NULL, ZERO);