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Olivier Fourdan fa6b40037a render: Avoid 0 or less animated cursors
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>
(cherry picked from commit 0885e0b262)

Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/2026>
2025-06-17 15:07:32 +02:00
.gitlab-ci CI: update libdecor from 0.1.0 to 0.1.1 2024-09-24 11:33:02 +02:00
composite composite: initialize border clip even when pixmap alloc fails 2025-02-25 19:38:11 +01:00
damageext Remove autotools support 2021-10-27 13:15:40 +03:00
dbe Drop Xorg DDX 2024-04-12 10:40:05 +02:00
dix dix: pick the right keyboard for focus FollowKeyboard 2025-04-08 10:06:12 +02:00
doc dix: dixutils: make workQueue pointer dix-private 2024-02-23 23:06:38 +00:00
dri3 Drop Xorg DDX 2024-04-12 10:40:05 +02:00
fb Drop Xorg DDX 2024-04-12 10:40:05 +02:00
glamor glamor: reject configs using unsupported rgbBits size 2025-02-04 18:14:06 +01:00
glx Drop Xorg DDX 2024-04-12 10:40:05 +02:00
hw pkgconfig files: Add URL 2025-04-08 10:05:31 +02:00
include dix-config.h: define HAVE_STRUCT_SOCKADDR_STORAGE for xtrans 1.6 2025-04-08 10:05:49 +02:00
man Drop Xorg DDX 2024-04-12 10:40:05 +02:00
mi mi: guard miPointer functions against NULL dereferences 2025-04-08 10:03:30 +02:00
miext Drop miext/shadow directory 2024-04-12 10:40:05 +02:00
os os/connection: Make sure partial is initialized 2025-02-04 09:21:13 +01:00
present build: Move epoll dependency check 2024-09-24 10:49:33 +02:00
randr Drop Xorg DDX 2024-04-12 10:40:05 +02:00
record dix: unexport eventconvert.h functions 2024-03-11 12:26:44 +01:00
render render: Avoid 0 or less animated cursors 2025-06-17 15:07:32 +02:00
test test: Fix xsync test 2025-02-25 19:38:08 +01:00
Xext sync: Apply changes last in SyncChangeAlarmAttributes() 2025-02-25 19:38:11 +01:00
xfixes Move sizeof to second argument in calloc calls 2024-08-06 10:00:59 +02:00
Xi Xi: disallow grabbing disabled devices 2025-04-08 10:04:53 +02:00
xkb xkb: Add tbGetBufferString helper function 2025-04-08 10:03:55 +02:00
.appveyor.yml Drop Xephyr / kdrive DDX 2024-04-12 10:40:05 +02:00
.dir-locals.el .dir-locals.el: Add missing final newline 2019-10-01 17:05:28 +00:00
.gitignore Clean up the .gitignore file 2024-01-12 00:50:24 +00:00
.gitlab-ci.yml CI: update libdecor from 0.1.0 to 0.1.1 2024-09-24 11:33:02 +02:00
.mailmap Add a .mailmap file to canonicalize author names and emails 2023-03-15 18:10:51 +00:00
COPYING modesetting: Merge modesetting's COPYING into the xserver's. 2014-09-15 12:46:02 -07:00
meson.build Bump version to 24.1.6 2025-02-25 19:38:11 +01:00
meson_options.txt meson: Build Xwayland unconditionally 2024-04-12 10:40:05 +02:00
README.md Fix spelling/wording issues 2020-07-05 13:07:33 -07:00
xserver.ent.in doc: relocate xserver.ent in the package root directory 2011-05-14 11:22:26 -07:00

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:

https://www.freedesktop.org/wiki/CodeOfConduct