xserver/render
Olivier Fourdan 0dca7ea49a 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>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/2024>
(cherry picked from commit 0885e0b262)
2026-01-25 10:40:01 -08:00
..
animcur.c render: Avoid 0 or less animated cursors 2026-01-25 10:40:01 -08:00
filter.c Convert top level extensions to new *allocarray functions 2015-04-21 16:57:08 -07:00
glyph.c render: Avoid possible double-free in ProcRenderAddGlyphs() 2026-01-19 12:32:25 -08:00
glyphstr.h render: fix refcounting of glyphs during ProcRenderAddGlyphs 2026-01-19 12:32:24 -08:00
matrix.c Introduce a consistent coding style 2012-03-21 13:54:42 -07:00
meson.build meson: hide C API if Xorg is disabled (like autotools) 2021-03-11 00:22:36 +00:00
miindex.c render: miindex.c does not need header guard macros 2026-01-25 10:40:01 -08:00
mipict.c dix: unexport Ones() 2026-01-25 10:39:57 -08:00
mipict.h render: Hide/unexport some implementation details 2015-07-08 16:40:57 -04:00
mirect.c render: Simplify miCompositeRects 2018-02-26 10:02:24 -05:00
mitrap.c Introduce a consistent coding style 2012-03-21 13:54:42 -07:00
mitri.c Introduce a consistent coding style 2012-03-21 13:54:42 -07:00
picture.c render: avoid NULL pointer dereference if PictureFindVisual returns NULL 2026-01-25 10:39:58 -08:00
picture.h glamor: fix CbCr format handling 2022-12-01 08:41:57 +00:00
picturestr.h render: Store and use all 16bpc of precision for solid pixels (v2.1) 2018-02-26 16:46:34 -05:00
render.c render: Avoid 0 or less animated cursors 2026-01-25 10:40:01 -08:00