xserver/composite
Olivier Fourdan d09125fbb3 composite: initialize border clip even when pixmap alloc fails
If it fails to allocate the pixmap, the function compAllocPixmap() would
return early and leave the borderClip region uninitialized, which may
lead to the use of uninitialized value as reported by valgrind:

 Conditional jump or move depends on uninitialised value(s)
    at 0x4F9B33: compClipNotify (compwindow.c:317)
    by 0x484FC9: miComputeClips (mivaltree.c:476)
    by 0x48559A: miValidateTree (mivaltree.c:679)
    by 0x4F0685: MapWindow (window.c:2693)
    by 0x4A344A: ProcMapWindow (dispatch.c:922)
    by 0x4A25B5: Dispatch (dispatch.c:560)
    by 0x4B082A: dix_main (main.c:282)
    by 0x429233: main (stubmain.c:34)
  Uninitialised value was created by a heap allocation
    at 0x4841866: malloc (vg_replace_malloc.c:446)
    by 0x4F47BC: compRedirectWindow (compalloc.c:171)
    by 0x4FA8AD: compCreateWindow (compwindow.c:592)
    by 0x4EBB89: CreateWindow (window.c:925)
    by 0x4A2E6E: ProcCreateWindow (dispatch.c:768)
    by 0x4A25B5: Dispatch (dispatch.c:560)
    by 0x4B082A: dix_main (main.c:282)
    by 0x429233: main (stubmain.c:34)

 Conditional jump or move depends on uninitialised value(s)
    at 0x48EEDBC: pixman_region_translate (pixman-region.c:2233)
    by 0x4F9255: RegionTranslate (regionstr.h:312)
    by 0x4F9B7E: compClipNotify (compwindow.c:319)
    by 0x484FC9: miComputeClips (mivaltree.c:476)
    by 0x48559A: miValidateTree (mivaltree.c:679)
    by 0x4F0685: MapWindow (window.c:2693)
    by 0x4A344A: ProcMapWindow (dispatch.c:922)
    by 0x4A25B5: Dispatch (dispatch.c:560)
    by 0x4B082A: dix_main (main.c:282)
    by 0x429233: main (stubmain.c:34)
  Uninitialised value was created by a heap allocation
    at 0x4841866: malloc (vg_replace_malloc.c:446)
    by 0x4F47BC: compRedirectWindow (compalloc.c:171)
    by 0x4FA8AD: compCreateWindow (compwindow.c:592)
    by 0x4EBB89: CreateWindow (window.c:925)
    by 0x4A2E6E: ProcCreateWindow (dispatch.c:768)
    by 0x4A25B5: Dispatch (dispatch.c:560)
    by 0x4B082A: dix_main (main.c:282)
    by 0x429233: main (stubmain.c:34)

 Conditional jump or move depends on uninitialised value(s)
    at 0x48EEE33: UnknownInlinedFun (pixman-region.c:2241)
    by 0x48EEE33: pixman_region_translate (pixman-region.c:2225)
    by 0x4F9255: RegionTranslate (regionstr.h:312)
    by 0x4F9B7E: compClipNotify (compwindow.c:319)
    by 0x484FC9: miComputeClips (mivaltree.c:476)
    by 0x48559A: miValidateTree (mivaltree.c:679)
    by 0x4F0685: MapWindow (window.c:2693)
    by 0x4A344A: ProcMapWindow (dispatch.c:922)
    by 0x4A25B5: Dispatch (dispatch.c:560)
    by 0x4B082A: dix_main (main.c:282)
    by 0x429233: main (stubmain.c:34)
  Uninitialised value was created by a heap allocation
    at 0x4841866: malloc (vg_replace_malloc.c:446)
    by 0x4F47BC: compRedirectWindow (compalloc.c:171)
    by 0x4FA8AD: compCreateWindow (compwindow.c:592)
    by 0x4EBB89: CreateWindow (window.c:925)
    by 0x4A2E6E: ProcCreateWindow (dispatch.c:768)
    by 0x4A25B5: Dispatch (dispatch.c:560)
    by 0x4B082A: dix_main (main.c:282)
    by 0x429233: main (stubmain.c:34)

Fix compAllocPixmap() to initialize the border clip even if the creation
of the backing pixmap has failed, to avoid depending later on
uninitialized border clip values.

Related to CVE-2025-26599, ZDI-CAN-25851

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Acked-by: Peter Hutterer <peter.hutterer@who-t.net>
(cherry picked from commit b07192a8be)

Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1830>
2025-02-25 19:36:29 +01:00
..
compalloc.c composite: initialize border clip even when pixmap alloc fails 2025-02-25 19:36:29 +01:00
compext.c dispatch: Mark swapped dispatch as _X_COLD 2017-03-01 10:16:20 -05:00
compinit.c composite: Stop wrapping GetImage/GetSpans 2019-10-30 16:26:01 +00:00
compint.h composite: Stop wrapping GetImage/GetSpans 2019-10-30 16:26:01 +00:00
compositeext.h composite: Export compIsAlternateVisual 2017-01-25 11:27:06 -05:00
compoverlay.c Drop trailing whitespaces 2014-11-12 10:25:00 +10:00
compwindow.c composite: Fix use-after-free of the COW 2023-03-29 14:20:26 +02:00
Makefile.am Export CompositeRegisterAlternateVisuals. 2009-04-27 13:29:40 -07:00
meson.build meson: hide C API if Xorg is disabled (like autotools) 2021-03-11 00:22:36 +00:00