0885e0b262
Animated cursors use a series of cursors that the client can set. By default, the Xserver assumes at least one cursor is specified while a client may actually pass no cursor at all. That causes an out-of-bound read creating the animated cursor and a crash of the Xserver: | Invalid read of size 8 | at 0x5323F4: AnimCursorCreate (animcur.c:325) | by 0x52D4C5: ProcRenderCreateAnimCursor (render.c:1817) | by 0x52DC80: ProcRenderDispatch (render.c:1999) | by 0x4A1E9D: Dispatch (dispatch.c:560) | by 0x4B0169: dix_main (main.c:284) | by 0x4287F5: main (stubmain.c:34) | Address 0x59aa010 is 0 bytes after a block of size 0 alloc'd | at 0x48468D3: reallocarray (vg_replace_malloc.c:1803) | by 0x52D3DA: ProcRenderCreateAnimCursor (render.c:1802) | by 0x52DC80: ProcRenderDispatch (render.c:1999) | by 0x4A1E9D: Dispatch (dispatch.c:560) | by 0x4B0169: dix_main (main.c:284) | by 0x4287F5: main (stubmain.c:34) | | Invalid read of size 2 | at 0x5323F7: AnimCursorCreate (animcur.c:325) | by 0x52D4C5: ProcRenderCreateAnimCursor (render.c:1817) | by 0x52DC80: ProcRenderDispatch (render.c:1999) | by 0x4A1E9D: Dispatch (dispatch.c:560) | by 0x4B0169: dix_main (main.c:284) | by 0x4287F5: main (stubmain.c:34) | Address 0x8 is not stack'd, malloc'd or (recently) free'd To avoid the issue, check the number of cursors specified and return a BadValue error in both the proc handler (early) and the animated cursor creation (as this is a public function) if there is 0 or less cursor. CVE-2025-49175 This issue was discovered by Nils Emmerich <nemmerich@ernw.de> and reported by Julian Suleder via ERNW Vulnerability Disclosure. Signed-off-by: Olivier Fourdan <ofourdan@redhat.com> Reviewed-by: José Expósito <jexposit@redhat.com> Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/2024>
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: