xterm crashes when compiz is on

[Leo Zhadanovsky]

Binary package hint: xterm

This seems to happen at random times when compiz is running on Ubuntu Gutsy on an x86_64 architecture:

xterm:
  Installed: 229-1
  Candidate: 229-1
  Version table:
 *** 229-1 0
        500 http://astromirror.uchicago.edu gutsy/main Packages
        100 /var/lib/dpkg/status

(gdb) run
Starting program: /usr/bin/xterm
[Thread debugging using libthread_db enabled]
[New Thread 47837066338144 (LWP 27542)]

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 47837066338144 (LWP 27542)]
0x0000000000430b42 in handle_translated_exposure (xw=0x6919d0, rect_x=0,
    rect_y=0, rect_width=579, rect_height=316) at ../util.c:1684
1684 ../util.c: No such file or directory.
        in ../util.c
(gdb) bt
#0 0x0000000000430b42 in handle_translated_exposure (xw=0x6919d0, rect_x=0,
    rect_y=0, rect_width=579, rect_height=316) at ../util.c:1684
#1 0x0000000000425544 in Redraw () at ../misc.c:1119
#2 0x000000000042cfd7 in ScrollBarOn (xw=0x6919d0,
    init=<value optimized out>, doalloc=1) at ../scrollbar.c:488
#3 0x000000000040ddaa in VTRealize (w=0x6919d0, valuemask=0x7fffbe46ad78,
    values=0x7fffbe46ace0) at ../charproc.c:6250
#4 0x00002b81ed3658a6 in ?? () from /usr/lib/libXt.so.6
#5 0x00002b81ed3659ee in ?? () from /usr/lib/libXt.so.6
#6 0x00002b81ed365c80 in XtRealizeWidget () from /usr/lib/libXt.so.6
#7 0x000000000040fe5b in VTInit () at ../charproc.c:4976
#8 0x000000000041e236 in spawnXTerm (xw=0x6919d0) at ../main.c:3245
#9 0x0000000000420257 in main (argc=0, argv=<value optimized out>)
    at ../main.c:2289
#10 0x00002b81edf4fb44 in __libc_start_main () from /lib/libc.so.6
#11 0x00000000004075b9 in _start ()

[Alexandre Kandalintsev (spam-messir)]

i've got i386 ubuntu 8.04 beta with all updates, but xterm segfaults too:
exe@hpc:~$ xterm
exe@hpc:~$ xterm
exe@hpc:~$ xterm
exe@hpc:~$ xterm
Segmentation fault
exe@hpc:~$ xterm
exe@hpc:~$ xterm
Segmentation fault
exe@hpc:~$ xterm

dmesg:
[ 927.659159] xterm[7524]: segfault at 0006b6d0 eip 08078573 esp bfe9d2a0 error 4
[ 935.539358] xterm[7627]: segfault at 0006b6d0 eip 08078573 esp bfe0ccf0 error 4
[ 937.095808] xterm[7645]: segfault at 0006b6d0 eip 08078573 esp bfb6f250 error 4

I can't provide backtrace as with gdb xterm didn't segfault.

[Bryce Harrington (bryce)]

The code in question is:

1684: leftcol = x0 / CurFontWidth(screen, screen->cur_row);
1685: if (leftcol < 0)
1686: leftcol = 0;

Maybe for whatever reason, CurFontWidth() returns 0 sometimes under Compiz?

[Bryce Harrington (bryce)]

Maybe try out this patch?

[Andrey Shytov (avshytov)]

I have a different suggestion. I traced out the relevant variables and found that CurFontWidth fails because screen->visbuf pointer is trashed. I figured out how it got that way: in the handling of a (premature?) resize event, when screen->allbuf == NULL. The patch is enclosed.

However, I am not sure this patch is the way to go. May be, the very fact that ScreenResize is executed at this stage indicates another bug?

[Bryce Harrington (bryce)]

I've forwarded the patch upstream for comment. Meanwhile, can anyone else test and verify the patch as solving the issue?

[Thomas Dickey (dickey-his)]

That might be the same as Fedora #437928 - fixed (I think) in xterm #235.

[Bryce Harrington (bryce)]

xterm 235-1ubuntu1 is in intrepid now. Based on the above comments, I'm assuming this to be fixed now. If not, please reopen.