Comment 13 for bug 247669

I am seeing this issue as well, very reproducible on my Dell 2950 server with
the stock RHEL5.1 ati driver and vnc-server packages.

Backtrace:
0: /usr/bin/Xorg(xf86SigHandler+0x71) [0x4a0921]
1: /lib64/libc.so.6 [0x315ac300b0]
2: /usr/bin/Xorg [0x4c28aa]
3: /usr/lib64/xorg/modules/libxaa.so [0x2aaaada10da7]
4: /usr/bin/Xorg [0x510449]
5: /usr/bin/Xorg [0x4d5ebc]
6:
/usr/lib64/xorg/modules/extensions/libvnc.so(_ZN14XserverDesktop10grabRegionERKN3rfb6RegionE+0x106)
[0x2aaaac26e346]
7:
/usr/lib64/xorg/modules/extensions/libvnc.so(_ZN3rfb11VNCServerST11checkUpdateEv+0x182)
[0x2aaaac2782a2]
8:
/usr/lib64/xorg/modules/extensions/libvnc.so(_ZN3rfb16VNCSConnectionST22writeFramebufferUpdateEv+0x96)
[0x2aaaac285ee6]
9:
/usr/lib64/xorg/modules/extensions/libvnc.so(_ZN3rfb16VNCSConnectionST24framebufferUpdateRequestERKNS_4RectEb+0xa6)
[0x2aaaac286606]
10:
/usr/lib64/xorg/modules/extensions/libvnc.so(_ZN3rfb10SMsgReader28readFramebufferUpdateRequestEv+0x180)
[0x2aaaac28bb80]
11:
/usr/lib64/xorg/modules/extensions/libvnc.so(_ZN3rfb16VNCSConnectionST15processMessagesEv+0x30)
[0x2aaaac285520]
12:
/usr/lib64/xorg/modules/extensions/libvnc.so(_ZN14XserverDesktop13wakeupHandlerEP6fd_seti+0xf0)
[0x2aaaac26dcc0]
13: /usr/lib64/xorg/modules/extensions/libvnc.so [0x2aaaac265ae9]
14: /usr/bin/Xorg(WakeupHandler+0x51) [0x44daa1]
15: /usr/bin/Xorg(WaitForSomething+0x1d4) [0x5509c4]
16: /usr/bin/Xorg(Dispatch+0x9a) [0x449b4a]
17: /usr/bin/Xorg(main+0x455) [0x4325b5]
18: /lib64/libc.so.6(__libc_start_main+0xf4) [0x315ac1d8a4]
19: /usr/bin/Xorg(FontFileCompleteXLFD+0x231) [0x4318a9]

xorg.conf (relevant parts):
Section "Module"
        Load "dbe"
        Load "extmod"
        Load "fbdevhw"
        Load "glx"
        Load "record"
        Load "freetype"
        Load "type1"
        Load "dri"
        Load "vnc"
EndSection

Section "Device"
        Identifier "Videocard0"
        Driver "ati"
        VendorName "Videocard vendor"
        BoardName "ATI ES1000"
EndSection

Section "Screen"
        Identifier "Screen0"
        Device "Videocard0"
        Monitor "Monitor0"
        DefaultDepth 16
        SubSection "Display"
                Viewport 0 0
                Depth 16
                Modes "1024x768" "800x600" "640x480"
        EndSubSection
        Option "SecurityTypes" "VncAuth"
        Option "passwordFile" "/etc/vnc/passwd"
EndSection

Pretty much makes VNC unusable.