mirror of
https://github.com/X11Libre/xserver.git
synced 2026-03-24 10:14:52 +00:00
215f894965
The SendEvent request holds xEvent which is exactly 32 bytes long, no more, no less. Both ProcSendEvent and SProcSendEvent verify that the received data exactly match the request size. However nothing stops the client from passing in event with xEvent::type = GenericEvent and any value of xGenericEvent::length. In the case of ProcSendEvent, the event will be eventually passed to WriteEventsToClient which will see that it is Generic event and copy the arbitrary length from the receive buffer (and possibly past it) and send it to the other client. This allows clients to copy unitialized heap memory out of X server or to crash it. In case of SProcSendEvent, it will attempt to swap the incoming event by calling a swapping function from the EventSwapVector array. The swapped event is written to target buffer, which in this case is local xEvent variable. The xEvent variable is 32 bytes long, but the swapping functions for GenericEvents expect that the target buffer has size matching the size of the source GenericEvent. This allows clients to cause stack buffer overflows. Signed-off-by: Michal Srb <msrb@suse.com> Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net> Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
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
Please submit bug reports to the Xorg bugzilla:
https://bugs.freedesktop.org/enter_bug.cgi?product=xorg
The master development code repository can be found at:
git://anongit.freedesktop.org/git/xorg/xserver
https://cgit.freedesktop.org/xorg/xserver
For patch submission instructions, see:
https://www.x.org/wiki/Development/Documentation/SubmittingPatches
For more information on the git code manager, see:
https://wiki.x.org/wiki/GitPage
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:
https://www.freedesktop.org/wiki/CodeOfConduct