PointerWindows[] keeps a reference to the last window our sprite
entered - changes are usually handled by CheckMotion().
If we switch between screens via XWarpPointer our
dev->spriteInfo->sprite->win is set to the new screen's root window.
If there's another window at the cursor location CheckMotion() will
trigger the right enter/leave events later. If there is not, it skips
that process and we never trigger LeaveWindow() - PointerWindows[] for
the device still refers to the previous window.
If that window is destroyed we have a dangling reference that will
eventually cause a use-after-free bug when checking the window hierarchy
later.
To trigger this, we require:
- two protocol screens
- XWarpPointer to the other screen's root window
- XDestroyWindow before entering any other window
This is a niche bug so we hack around it by making sure we reset the
PointerWindows[] entry so we cannot have a dangling pointer. This
doesn't handle Enter/Leave events correctly but the previous code didn't
either.
CVE-2023-5380, ZDI-CAN-21608
This vulnerability was discovered by:
Sri working with Trend Micro Zero Day Initiative
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Adam Jackson <ajax@redhat.com>
(cherry picked from commit
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Xext | ||
Xi | ||
composite | ||
config | ||
damageext | ||
dbe | ||
dix | ||
doc | ||
dri3 | ||
exa | ||
fb | ||
glamor | ||
glx | ||
hw | ||
include | ||
m4 | ||
man | ||
mi | ||
miext | ||
os | ||
present | ||
pseudoramiX | ||
randr | ||
record | ||
render | ||
test | ||
xfixes | ||
xkb | ||
.appveyor.yml | ||
.dir-locals.el | ||
.gitignore | ||
.gitlab-ci.yml | ||
.travis.yml | ||
COPYING | ||
Makefile.am | ||
README.md | ||
autogen.sh | ||
configure.ac | ||
devbook.am | ||
docbook.am | ||
manpages.am | ||
meson.build | ||
meson_options.txt | ||
xorg-server.m4 | ||
xorg-server.pc.in | ||
xserver.ent.in |
X Server
The X server accepts requests from client applications to create windows, which are (normally rectangular) "virtual screens" that the client program can draw into.
Windows are then composed on the actual screen by the X server (or by a separate composite manager) as directed by the window manager, which usually communicates with the user via graphical controls such as buttons and draggable titlebars and borders.
For a comprehensive overview of X Server and X Window System, consult the following article: https://en.wikipedia.org/wiki/X_server
All questions regarding this software should be directed at the Xorg mailing list:
https://lists.freedesktop.org/mailman/listinfo/xorg
The primary development code repository can be found at:
https://gitlab.freedesktop.org/xorg/xserver
For patch submission instructions, see:
https://www.x.org/wiki/Development/Documentation/SubmittingPatches
As with other projects hosted on freedesktop.org, X.Org follows its Code of Conduct, based on the Contributor Covenant. Please conduct yourself in a respectful and civilized manner when using the above mailing lists, bug trackers, etc: