Description of problem:

Some software GL op crashes the X server. Using the nv driver.

Version-Release number of selected component (if applicable):

xorg-x11-server-Xorg-1.1.1-43.fc6
mesa-libGL-6.5.1-7.fc6
xorg-x11-drv-nv-1.2.0-4.fc6

How reproducible:

Every time.

Steps to Reproduce:
1. Start up X on nv card. (nVidia Corporation NV34GL [Quadro FX 500/600 PCI]
(rev a1))
2. Install xscreensaver-gl-extras
3. Run /usr/libexec/xscreensaver/glblur
4. Wince in pain
5. Drag it around, resize it, etc.
  
Actual results:


Program received signal SIGSEGV, Segmentation fault.
0x00002aaab726847f in _swrast_depth_test_span (ctx=0x17a5790, span=0x7fffcb886b10)
    at s_depth.c:577
577                       if (z[i] < *zptr) {
#0  0x00002aaab726847f in _swrast_depth_test_span (ctx=0x17a5790,
span=0x7fffcb886b10)
    at s_depth.c:577
#1  0x00002aaab726572e in _swrast_write_rgba_span (ctx=0x17a5790,
span=0x7fffcb886b10)
    at s_span.c:1245
#2  0x00002aaab7295269 in draw_wide_line (ctx=0x17a5790, span=0x7fffcb886b10, 
    xMajor=<value optimized out>) at s_lines.c:91
#3  0x00002aaab72963e1 in general_rgba_line (ctx=0x17a5790, vert0=<value
optimized out>, 
    vert1=0x89a4) at s_linetemp.h:430
#4  0x00002aaab72c4935 in clip_render_lines_verts (ctx=0x17a5790, start=0, count=8, 
    flags=<value optimized out>) at t_vb_rendertmp.h:85
#5  0x00002aaab72c889a in run_render (ctx=0x17a5790, stage=<value optimized out>)
    at t_vb_render.c:320
#6  0x00002aaab72e4b4b in _tnl_run_pipeline (ctx=0x17a5790) at t_pipeline.c:159
#7  0x00002aaab72c9134 in _tnl_playback_vertex_list (ctx=0x17a5790, 
    data=<value optimized out>) at t_save_playback.c:209
#8  0x00002aaab71f8107 in execute_list (ctx=0x17a5790, list=<value optimized out>)
    at dlist.c:5783
#9  0x00002aaab71f8362 in execute_list (ctx=0x17a5790, list=<value optimized out>)
    at dlist.c:5826
#10 0x00002aaab71fab17 in _mesa_CallList (list=6) at dlist.c:6875
#11 0x00002aaaabfac8a7 in __glXRender (cl=<value optimized out>, pc=<value
optimized out>)
    at glxcmds.c:1739
#12 0x00002aaaabfb10c8 in __glXDispatch (client=<value optimized out>) at
glxext.c:522
#13 0x0000000000449c9a in Dispatch () at dispatch.c:459
#14 0x00000000004325d5 in main (argc=9, argv=0x7fffcb888238, envp=<value
optimized out>)
    at main.c:447