Bug 1468 - SIGSEGV on use after free when destroying NEWT Window/Display via a native dispatch'ed event like key/mouse/touch input

SIGSEGV on use after free of native X11 Display* at XEventsQueued in DisplayDriver.DispatchMessages0.

This potentially happens when an application destroys
the NEWT Window/Display from an action being called directly
from DisplayDriver.DispatchMessages0 (itself), i.e. keyboard or mouse input.

DisplayDriver.DispatchMessages0 stays in the event loop and the next
XEventsQueued call causes a SIGSEGV due to already deleted
display driver connection and hence invalid native X11 Display*.

This issue also exist for other Windowing System drivers,
where the native (dispatch) method sticks to a loop
and still (re)uses the window or display handle.

One is WindowsWindow, where touch events are looped,
but such handler could have closed the window.

Querying the status of a window / display instance before dispatching
is not be good enough
- resource could already be GC'ed, so we also would need to query jobject status
- would imply an addition Java callback

+++

This fix: Having the Java callbacks return
a boolean with the value Window.isNativeValid().

This way the dispatch logic
- can bail out right away w/o using the resource anymore

- must be reviewed by myself due to changed Call{Void->Boolean}*(..)
  invocation change.
  This review shall resolve potential similar issues.

+++

Tested on X11/Linux/GNU, Windows and MacOS
with new TestDestroyGLAutoDrawableNewtAWT,
which tests all destruction invocation variants.

0 files changed, 0 insertions, 0 deletions