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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>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1828>
This commit is contained in:
Olivier Fourdan 2025-01-13 16:09:43 +01:00
parent c1ff84bef2
commit b07192a8be
1 changed files with 8 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
composite/compalloc.c
View File

@ -605,9 +605,12 @@ compAllocPixmap(WindowPtr pWin)
int h = pWin->drawable.height + (bw << 1);
PixmapPtr pPixmap = compNewPixmap(pWin, x, y, w, h);
CompWindowPtr cw = GetCompWindow(pWin);
Bool status;
if (!pPixmap)
return FALSE;
if (!pPixmap) {
status = FALSE;
goto out;
}
if (cw->update == CompositeRedirectAutomatic)
pWin->redirectDraw = RedirectDrawAutomatic;
else
@ -621,14 +624,16 @@ compAllocPixmap(WindowPtr pWin)
DamageRegister(&pWin->drawable, cw->damage);
cw->damageRegistered = TRUE;
}
status = TRUE;
out:
/* Make sure our borderClip is up to date */
RegionUninit(&cw->borderClip);
RegionCopy(&cw->borderClip, &pWin->borderClip);
cw->borderClipX = pWin->drawable.x;
cw->borderClipY = pWin->drawable.y;
return TRUE;
return status;
}
void