Package: libxext6 Version: 2:1.3.3-1.1 Severity: minor Tags: upstream X-Debbugs-Cc: s...@debian.org
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Hi,
I have a very basic Vulkan app that uses libXext only indirectly through
the Vulkan X11 extension, so my program is not linked against libXext
directly (and can be linked only with --no-as-needed).
During shutdown, the program crashes with a segmentation fault, during
63 for (ext = dpy->ext_procs; ext; ext = ext->next) {
64 if (ext->close_display)
65 (*ext->close_display)(dpy, &ext->codes);
from src/ClDisplay.c in libX11. According to gdb,
*ext = {next = 0x5555558d0ee0, codes = {extension = 2, major_opcode = 128,
first_event = 0, first_error = 0}, create_GC = 0x0, copy_GC = 0x0,
flush_GC = 0x0, free_GC = 0x0, create_Font = 0x0, free_Font = 0x0,
close_display = 0x7fffed9c6ce0, error = 0x0, error_string = 0x0,
name = 0x5555558d0ec0 "Generic Event Extension", error_values = 0x0,
before_flush = 0x0, next_flush = 0x0}
The address for close_display refers to
0x00007fffed9bd3d0 0x00007fffed9c74ff Yes (*)
/lib/x86_64-linux-gnu/libXext.so.6
which has been unloaded at this point, together with the Vulkan driver.
It seems that libXext expects that it will remain loaded until
CloseDisplay() time, which is difficult to do here: I need to dismantle
Vulkan before closing the display connection, and libXext is only used
by an extension module that is loaded with dlopen(), so libXext will be
unloaded during Vulkan stack teardown.
I could reproduce this with both Intel and nVidia GPUs, using the source
attached. The problem goes away if I configure with
./configure LIBS='-Wl,--no-as-needed,-lXext'
to force link the application against libXext.
Simon
- -- System Information:
Debian Release: 11.2
APT prefers stable
APT policy: (990, 'stable'), (500, 'stable-updates'), (500,
'stable-security'), (500, 'stable-debug'), (500, 'proposed-updates-debug'),
(500, 'unstable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386
Kernel: Linux 5.10.0-9-amd64 (SMP w/8 CPU threads)
Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE
Locale: LANG=C.UTF-8, LC_CTYPE=C.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: sysvinit (via /sbin/init)
LSM: AppArmor: enabled
Versions of packages libxext6 depends on:
ii libc6 2.31-13+deb11u2
ii libx11-6 2:1.7.2-1
libxext6 recommends no packages.
libxext6 suggests no packages.
- -- no debconf information
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vkload-0.0.20211229.tar.gz
Description: application/gzip
