Xserver crashes when drawing multi-segment dashed lines that
extend outside visible window. Running Linux, Opensuse 13.1
with kernel 3.17. Running on i5-2500K using on-board graphics.
X server is version 7.6_1.16.1, Intel driver is version
2.99.916
The crash occurs both on KDE and icewm.

After a crash, log file shows the following
---------------- begin log segment --------------
[  3111.676] (EE) 14: /usr/bin/Xorg (0x400000+0x2cba1) [0x42cba1]
[  3111.676] (EE) 
[  3111.676] (EE) Segmentation fault at address 0x7fffdf4a1004
[  3111.676] (EE) 
Fatal server error:
[  3111.676] (EE) Caught signal 11 (Segmentation fault). Server aborting
[  3111.676] (EE) 
[  3111.676] (EE) 
Please consult the The X.Org Foundation support 
	 at http://wiki.x.org
 for help. 
----------------- end log segment ----------------

The crash can be reproduced by the short program listed below.
It does not crash on every draw call, hence the program loop.
Usually it crashes in < 100 iterations of the loop.

The conditions for crashing are fairly specific; if you make
_any_ of the following changes to the test program, it will no
longer crash:
a) Increase the window size to 600x600
b) Change the line width to 2 or more
c) For equal on-off dashes, set the dash length to something
   which is not 3, 8, 9, 10, 15, 17 or 19 (These are the only
   dash lengths <= 20 which cause the crash).
d) Change the join to JoinMiter   
   
---------------------- Test program -----------------
/* compile with  
gcc -O2 -Wall -o x5 x5.c -L /usr/X11R6/lib -lX11 -lm
*/
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
 #include <stdio.h>
 #include <stdlib.h>

   XPoint pts[] = {
   {229, 229}, {223, 234}, {217, 240}, {211, 246}, {205, 252}, {200, 258}, {195, 264}, {189, 270}, 
   {184, 276}, {179, 282}, {174, 288}, {169, 294}, {164, 300}, {160, 306}, {155, 312}, {151, 318}, 
   {146, 324}, {142, 330}, {138, 336}, {134, 341}, {130, 347}, {126, 353}, {123, 358}, {119, 364}, 
   {116, 370}, {113, 375}, {109, 381}, {106, 386}, {104, 391}, {101, 397}, { 98, 402}, { 96, 407}, 
   { 93, 412}, { 91, 417}, { 89, 422}, { 87, 427}, { 86, 432}, { 84, 436}, { 82, 441}, { 81, 445}, 
   { 80, 450}, { 79, 454}, { 78, 458}, { 77, 462}, { 77, 466}, { 76, 470}, { 76, 474}, { 76, 478}, 
   { 76, 481}, { 76, 485}, { 77, 488}, { 77, 491}, { 78, 494}, { 79, 497}, { 80, 500}, { 81, 502}, 
   { 82, 505}, { 84, 507}, { 86, 509}, { 88, 512}
   };

   Display *d;
   int s;
   GC gc;
 
int main() {
   int i;
   Window w;
   XEvent e;
   unsigned int width = 1;
   char dash[] = {3,3};
   int join = JoinBevel;
   int CYCLES = 50000;
   
   d=XOpenDisplay(NULL);
   if(d==NULL) {
     printf("Cannot open display\n");
     exit(1);
   }
   s=DefaultScreen(d);
   gc = XDefaultGC(d, s);
   
   XSetLineAttributes(d, gc, width, LineOnOffDash, CapButt, join);

   w=XCreateSimpleWindow(d, RootWindow(d, s), 100, 100, 400, 400, 1,
                         BlackPixel(d, s), WhitePixel(d, s));

   XSelectInput(d, w, ExposureMask | KeyPressMask);
 
   XMapWindow(d, w);

   while(1) {
     XNextEvent(d, &e);
     if(e.type==Expose) {
         printf("Running\n");
         XSetDashes(d, gc, 0, dash, sizeof(dash));
         
         for (i=0; i<CYCLES;  i++){
            XClearWindow(d, w);
            XSetForeground(d, gc, 0x0000ff);
            XDrawLines(d, w, gc, pts, sizeof(pts)/sizeof(XPoint), CoordModeOrigin);
            XFlush(d);
         }
         printf("Done %d cycles\n", CYCLES);
      }
                        /* exit on key press */
     if(e.type==KeyPress) {
         break;
     }
   } 
   XDestroyWindow(d, w);
   XCloseDisplay(d);
   return 0;
}
-------------- End of test program -----------------