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PointerWindows[] keeps a reference to the last window our sprite
entered - changes are usually handled by CheckMotion().
If we switch between screens via XWarpPointer our
dev->spriteInfo->sprite->win is set to the new screen's root window.
If there's another window at the cursor location CheckMotion() will
trigger the right enter/leave events later. If there is not, it skips
that process and we never trigger LeaveWindow() - PointerWindows[] for
the device still refers to the previous window.
If that window is destroyed we have a dangling reference that will
eventually cause a use-after-free bug when checking the window hierarchy
later.
To trigger this, we require:
- two protocol screens
- XWarpPointer to the other screen's root window
- XDestroyWindow before entering any other window
This is a niche bug so we hack around it by making sure we reset the
PointerWindows[] entry so we cannot have a dangling pointer. This
doesn't handle Enter/Leave events correctly but the previous code didn't
either.
CVE-2023-5380, ZDI-CAN-21608
This vulnerability was discovered by:
Sri working with Trend Micro Zero Day Initiative
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Adam Jackson <ajax@redhat.com>
(cherry picked from commit
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| .. | ||
| .gitignore | ||
| atom.c | ||
| buildatoms | ||
| BuiltInAtoms | ||
| colormap.c | ||
| cursor.c | ||
| devices.c | ||
| dispatch.c | ||
| dispatch.h | ||
| dixfonts.c | ||
| dixutils.c | ||
| enterleave.c | ||
| enterleave.h | ||
| eventconvert.c | ||
| events.c | ||
| extension.c | ||
| gc.c | ||
| gestures.c | ||
| getevents.c | ||
| globals.c | ||
| glyphcurs.c | ||
| grabs.c | ||
| initatoms.c | ||
| inpututils.c | ||
| main.c | ||
| Makefile.am | ||
| meson.build | ||
| pixmap.c | ||
| privates.c | ||
| property.c | ||
| protocol.txt | ||
| ptrveloc.c | ||
| region.c | ||
| registry.c | ||
| resource.c | ||
| selection.c | ||
| stubmain.c | ||
| swaprep.c | ||
| swapreq.c | ||
| tables.c | ||
| touch.c | ||
| window.c | ||