valgrind callstack for an invalid read access

gistfile1.txt

==9341== Invalid read of size 4
==9341==    at 0x40A508: weston_surface_from_global_float (compositor.c:774)
==9341==    by 0x40A64C: weston_surface_from_global_fixed (compositor.c:803)
==9341==    by 0x40AC36: weston_compositor_pick_surface (compositor.c:959)
==9341==    by 0x40E251: default_grab_focus (input.c:109)
==9341==    by 0x40E614: notify_motion_absolute (input.c:663)
==9341==    by 0x88444EB: xf_mouseEvent (compositor-rdp.c:771)
==9341==    by 0x8CA39EA: fastpath_recv_inputs (in /home/david/dev/install/lib/x86_64-linux-gnu/libfreerdp-core.so.1.1.0)
==9341==    by 0x8CADB7E: peer_recv_pdu (in /home/david/dev/install/lib/x86_64-linux-gnu/libfreerdp-core.so.1.1.0)
==9341==    by 0x8CADFFF: peer_recv_callback (in /home/david/dev/install/lib/x86_64-linux-gnu/libfreerdp-core.so.1.1.0)
==9341==    by 0x8CA54FA: transport_check_fds (in /home/david/dev/install/lib/x86_64-linux-gnu/libfreerdp-core.so.1.1.0)
==9341==    by 0x8CADA42: freerdp_peer_check_fds (in /home/david/dev/install/lib/x86_64-linux-gnu/libfreerdp-core.so.1.1.0)
==9341==    by 0x884497C: rdp_client_activity (compositor-rdp.c:616)
==9341==  Address 0x108ffb48 is 392 bytes inside a block of size 896 free'd
==9341==    at 0x4C2BA6C: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==9341==    by 0x4E3DAA7: wl_map_for_each (wayland-util.c:309)
==9341==    by 0x4E39B47: wl_client_destroy (wayland-server.c:467)
==9341==    by 0x4E3A1A4: wl_display_flush_clients (wayland-server.c:724)
==9341==    by 0x4E3A1E7: wl_display_run (wayland-server.c:706)
==9341==    by 0x407E36: main (compositor.c:3322)
==9341==