Bug 1444490

While trying to figure out bug #1444405 I noticed under valgrind an invalid write from atk-spi, which can cause the error in bug #1444405, due to overwriting memory which is not its.

This is with:
glib2-2.50.3-2.el7.x86_64
gtk3-3.22.10-3.el7.x86_64
evolution-3.22.6-8.el7.x86_64
atk-2.22.0-1.el7.x86_64
at-spi2-atk-2.22.0-1.el7.x86_64
dbus-1.6.12-17.el7.x86_64


Steps:
a) have enabled accessibility in the system + enable also Screen reader
b) open terminal and run from there:
   $ G_SLICE=always-malloc valgrind evolution
c) once evolution opens, click the New button, which opens the composer
d) once composer is there, switch back to evolution and close it

That's the moment when the below valgrind log shows up. To make it clear, the composer window is still there, it's only the main window of Evolution which had been closed.

As this is invalid write, it overwrites some "random" chunk of 8 bytes in memory, effectively causing memory corruption in whatever place the memory got occupied with. Such things are hard to reproduce, but it seems the test from bug #1444405 can reproduce the crash consistently when run under behave. I see the valgrind log consistently too, but it doesn't break things always, especially when not run under valgrind.

==2809== Thread 1:
==2809== Invalid write of size 8
==2809==    at 0x18FCF001: remove_events (bridge.c:759)
==2809==    by 0x18FCF001: handle_event_listener_deregistered (bridge.c:788)
==2809==    by 0x18FCF001: signal_filter (bridge.c:827)
==2809==    by 0x200ECDFD: dbus_connection_dispatch (dbus-connection.c:4631)
==2809==    by 0x1FEBD0F4: ??? (in /usr/lib64/libatspi.so.0.0.1)
==2809==    by 0xFD8D4C8: g_main_dispatch (gmain.c:3201)
==2809==    by 0xFD8D4C8: g_main_context_dispatch (gmain.c:3854)
==2809==    by 0xFD8D817: g_main_context_iterate.isra.21 (gmain.c:3927)
==2809==    by 0xFD8DAE9: g_main_loop_run (gmain.c:4123)
==2809==    by 0xDFF84B4: gtk_main (in /usr/lib64/libgtk-3.so.0.2200.10)
==2809==    by 0x403DE0: main (in /usr/bin/evolution)
==2809==  Address 0x29f22540 is 16 bytes inside a block of size 24 free'd
==2809==    at 0x4C2ACDD: free (vg_replace_malloc.c:530)
==2809==    by 0xFD92BCD: g_free (gmem.c:189)
==2809==    by 0xFDAA518: g_slice_free1 (gslice.c:1136)
==2809==    by 0xFD89463: g_list_remove (glist.c:521)
==2809==    by 0x18FCF000: remove_events (bridge.c:759)
==2809==    by 0x18FCF000: handle_event_listener_deregistered (bridge.c:788)
==2809==    by 0x18FCF000: signal_filter (bridge.c:827)
==2809==    by 0x200ECDFD: dbus_connection_dispatch (dbus-connection.c:4631)
==2809==    by 0x1FEBD0F4: ??? (in /usr/lib64/libatspi.so.0.0.1)
==2809==    by 0xFD8D4C8: g_main_dispatch (gmain.c:3201)
==2809==    by 0xFD8D4C8: g_main_context_dispatch (gmain.c:3854)
==2809==    by 0xFD8D817: g_main_context_iterate.isra.21 (gmain.c:3927)
==2809==    by 0xFD8DAE9: g_main_loop_run (gmain.c:4123)
==2809==    by 0xDFF84B4: gtk_main (in /usr/lib64/libgtk-3.so.0.2200.10)
==2809==    by 0x403DE0: main (in /usr/bin/evolution)
==2809==  Block was alloc'd at
==2809==    at 0x4C29BE3: malloc (vg_replace_malloc.c:299)
==2809==    by 0xFD92ABD: g_malloc (gmem.c:94)
==2809==    by 0xFDA9EFD: g_slice_alloc (gslice.c:1025)
==2809==    by 0xFD89983: g_list_append (glist.c:261)
==2809==    by 0x18FCE7EE: add_event (bridge.c:80)
==2809==    by 0x18FCE7EE: add_event_from_iter (bridge.c:217)
==2809==    by 0x18FCEEF6: handle_event_listener_registered (bridge.c:721)
==2809==    by 0x18FCEEF6: signal_filter (bridge.c:825)
==2809==    by 0x200ECDFD: dbus_connection_dispatch (dbus-connection.c:4631)
==2809==    by 0x1FEBD0F4: ??? (in /usr/lib64/libatspi.so.0.0.1)
==2809==    by 0xFD8D4C8: g_main_dispatch (gmain.c:3201)
==2809==    by 0xFD8D4C8: g_main_context_dispatch (gmain.c:3854)
==2809==    by 0xFD8D817: g_main_context_iterate.isra.21 (gmain.c:3927)
==2809==    by 0xFD8DAE9: g_main_loop_run (gmain.c:4123)
==2809==    by 0xDFF84B4: gtk_main (in /usr/lib64/libgtk-3.so.0.2200.10)