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>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1828>
b07192a8be