backend: fix use-after-free when destroying backends

The backend destroy signal is emitted before the output_remove
signal is. When the destroy signal is emitted listeners remove
their output_remove listener, so the output_remove signal is never
received and listeners have an invalid output pointer.

The correct way to solve this would be to remove the output_remove
signal completely and use the wlr_output.events.destroy signal
instead. This isn't yet possible because wl_signal_emit is unsafe
and listeners cannot be removed in listeners.
This commit is contained in:
emersion 2018-01-30 19:45:57 +01:00
parent 704130cc11
commit babdd6ccf7
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10 changed files with 27 additions and 13 deletions

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@ -42,11 +42,16 @@ static void subbackend_state_destroy(struct subbackend_state *sub) {
static void multi_backend_destroy(struct wlr_backend *wlr_backend) {
struct wlr_multi_backend *backend = (struct wlr_multi_backend *)wlr_backend;
wl_list_remove(&backend->display_destroy.link);
struct subbackend_state *sub, *next;
wl_list_for_each_safe(sub, next, &backend->backends, link) {
wlr_backend_destroy(sub->backend);
}
// Destroy this backend only after removing all sub-backends
wl_signal_emit(&wlr_backend->events.destroy, backend);
free(backend);
}