11fcda8753
The code in XkbVModMaskText() allocates a fixed sized buffer on the stack and copies the virtual mod name. There's actually two issues in the code that can lead to a buffer overflow. First, the bound check mixes pointers and integers using misplaced parenthesis, defeating the bound check. But even though, if the check fails, the data is still copied, so the stack overflow will occur regardless. Change the logic to skip the copy entirely if the bound check fails. CVE-2025-26595, ZDI-CAN-25545 This vulnerability was discovered by: Jan-Niklas Sohn working with Trend Micro Zero Day Initiative Signed-off-by: Olivier Fourdan <ofourdan@redhat.com> Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net> Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1828>
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
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