Bug#1032984: libx11-6 version 2:1.8.4-2 regression

Stefan Schippers

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Mar 15, 2023, 4:30:06 AM3/15/23

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Package: libx11-6
Version: 2:1.8.4-2

I have frequent fvwm window manager crashes due to an assertion in libX11 that causes
a SIGABRT and window manager crash.
This bug is related to #1032379, if you go down to the thread it is triggered by the
same assertion.
I do not use a desktop environment, I just start X by using startx and use the fvwm2
window manager. The message printed from fvwm is:

fvwm: ../../src/xcb_io.c:626: _XAllocID: Assertion `ret != inval_id' failed.

I can reliably crash the window manager by doing some mouse actions in the root window
(minimize, maximize windows, resize windows).

I have reverted the following packages to 2:1.8.3-3 and no failures happen any more,
even after intensive stress tests:

libx11-6
libx11-data
libx11-dev
libx11-xcb-dev
libx11-xcb1

Backtrace of failed fvwm process follows.
Thank you.

Stefan

This is the backtrace of the failed fvwm process:

(gdb) run
Starting program: /usr/bin/fvwm
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Detaching after fork from child process 4851]
[Detaching after vfork from child process 4864]
Warning: Arg --fvwm-icons is obsolete and ignored
Python module python-xdg not found.fvwm: ../../src/xcb_io.c:626: _XAllocID: Assertion `ret != inval_id' failed.

Program received signal SIGABRT, Aborted.
__pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at ./nptl/pthread_kill.c:44
44 ./nptl/pthread_kill.c: No such file or directory.
(gdb) bt
#0 __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at ./nptl/pthread_kill.c:44
#1 0x00007ffff6ca9d2f in __pthread_kill_internal (signo=6, threadid=<optimized out>) at ./nptl/pthread_kill.c:78
#2 0x00007ffff6c5aef2 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
#3 0x00007ffff6c45472 in __GI_abort () at ./stdlib/abort.c:79
#4 0x00007ffff6c45395 in __assert_fail_base
(fmt=0x7ffff6db9a70 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=assertion@entry=0x7ffff7b75b2a "ret != inval_id", file=file@entry=0x7ffff7b75a9b "../../src/xcb_io.c", line=line@entry=626, function=function@entry=0x7ffff7b75ef0 "_XAllocID") at ./assert/assert.c:92
#5 0x00007ffff6c53df2 in __GI___assert_fail (assertion=0x7ffff7b75b2a "ret != inval_id", file=0x7ffff7b75a9b "../../src/xcb_io.c", line=626, function=0x7ffff7b75ef0 "_XAllocID") at ./assert/assert.c:101
#6 0x00007ffff7b02443 in () at /usr/lib/x86_64-linux-gnu/libX11.so.6
#7 0x00007ffff7e56558 in XRenderCreatePicture () at /usr/lib/x86_64-linux-gnu/libXrender.so.1
#8 0x00007ffff7f9e5b6 in () at /usr/lib/x86_64-linux-gnu/libXft.so.2
#9 0x00007ffff7f9ec95 in XftDrawGlyphs () at /usr/lib/x86_64-linux-gnu/libXft.so.2
#10 0x00007ffff7f9f2ad in XftDrawStringUtf8 () at /usr/lib/x86_64-linux-gnu/libXft.so.2
#11 0x00005555555ff843 in ()
#12 0x00005555555e6dfb in ()
#13 0x00005555555a5fff in ()
#14 0x00005555555a7ba4 in ()
#15 0x0000555555588dba in ()
#16 0x000055555558c4eb in ()
#17 0x000055555558c66c in ()
#18 0x0000555555600189 in ()
#19 0x000055555560020f in ()
#20 0x00007ffff7add9da in XCheckIfEvent () at /usr/lib/x86_64-linux-gnu/libX11.so.6
#21 0x0000555555600b62 in ()
#22 0x0000555555600cb7 in ()
#23 0x000055555558d58a in ()
#24 0x00005555555bfb2f in ()
#25 0x00005555555a92ca in ()
#26 0x00005555555a9bf4 in ()
#27 0x00005555555c7f29 in ()
#28 0x0000555555589d43 in ()
#29 0x000055555558c4eb in ()
#30 0x000055555558c5e4 in ()
#31 0x00005555555674f7 in ()
#32 0x00007ffff6c4618a in __libc_start_call_main (main=main@entry=0x555555565a90, argc=argc@entry=1, argv=argv@entry=0x7fffffffe4d8) at ../sysdeps/nptl/libc_start_call_main.h:58
#33 0x00007ffff6c46245 in __libc_start_main_impl (main=0x555555565a90, argc=1, argv=0x7fffffffe4d8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffe4c8) at ../csu/libc-start.c:381
#34 0x0000555555568631 in ()
(gdb)

Timo Aaltonen

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Mar 15, 2023, 5:40:04 AM3/15/23

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Well, it still needs someone to file a bug upstream.

--
t

Stefan Schippers

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Mar 15, 2023, 7:20:04 PM3/15/23

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Package: libx11-6
Version: 2:1.8.4-2

Bug: #1032984

The issue has been filed upstream.
https://gitlab.freedesktop.org/xorg/lib/libx11/-/issues/186

Stefan

On 3/15/23 09:27, Debian Bug Tracking System wrote:
> Thank you for filing a new Bug report with Debian.
>
> You can follow progress on this Bug here: 1032984: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1032984.
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Stefan Schippers

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Mar 26, 2023, 4:10:04 PM3/26/23

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I have closed upstream bug:
https://gitlab.freedesktop.org/xorg/lib/libx11/-/issues/186
since i got no feedback at all and it seems affecting only the specific
libX11 1.8.4 - fvwm2 combination that very few people use, I think.

The dirty fix for me was to switch from fvwm2 to the developing fvwm3 window manager.

I don't know if the window manager crash is due to a libX11 bug or to library
API misuse by fvwm2. The problem appeared after a recent libX11 update
(1.8.3 -> 1.8.4) while fvwm2 is frozen since long time.

Stefan

Julien Cristau

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Apr 3, 2023, 10:30:04 AM4/3/23

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On Sun, Mar 26, 2023 at 22:03:25 +0200, Stefan Schippers wrote:

> I have closed upstream bug:
> https://gitlab.freedesktop.org/xorg/lib/libx11/-/issues/186
> since i got no feedback at all and it seems affecting only the specific
> libX11 1.8.4 - fvwm2 combination that very few people use, I think.
>

Expecting a response within a few days was probably unrealistic in the
first place...

Cheers,
Julien

Stefan Schippers

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Apr 4, 2023, 3:20:06 AM4/4/23

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You are right, but it seems the bug is very specific to the libX11 1.8.4 + fvwm2 combination
There is basically no other report about this, all other applications for me work fine with 1.8.4,
so at the end of the day I don't want to waste developers time with something that is probably not
a libX11 bug. Switching from fvwm2 (frozen project) to fvwm3 (active project) solved the
issue for me.