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Fix use after free error rendering in background mode on Wayland

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The event handing thread wasn't properly shutdown in background mode.

Resolve by disabling threaded event handling in background mode.
This commit is contained in:
Campbell Barton
2025-05-30 12:26:14 +10:00
parent fbe28d16bd
commit 60aede77af
1 changed files with 44 additions and 10 deletions
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54
intern/ghost/intern/GHOST_SystemWayland.cc
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@@ -1493,14 +1493,30 @@ struct GWL_Display {
*/
int seats_active_index = 0;
/**
* When true, running without any windows.
* Wayland is only used to access the GPU.
*
* \note In general logic should not diverge too much in background mode,
* so as to avoid maintaining multiple code-paths however some logic can be skipped
* such as libraries for showing window decorations and threaded event handling.
*/
bool background = false;
/* Threaded event handling. */
#ifdef USE_EVENT_BACKGROUND_THREAD
/**
* Run a thread that consumes events in the background.
* Use `pthread` because `std::thread` leaks memory.
*
* Not set when `background == true`.
*/
pthread_t events_pthread = 0;
/** Use to exit the event reading loop. */
/**
* Use to exit the event reading loop.
*
* Not set when `background == true`.
*/
bool events_pthread_is_active = false;
/**
@@ -1533,9 +1549,11 @@ struct GWL_Display {
static void gwl_display_destroy(GWL_Display *display)
{
#ifdef USE_EVENT_BACKGROUND_THREAD
if (display->events_pthread) {
ghost_wl_display_lock_without_input(display->wl.display, display->system->server_mutex);
display->events_pthread_is_active = false;
if (!display->background) {
if (display->events_pthread) {
ghost_wl_display_lock_without_input(display->wl.display, display->system->server_mutex);
display->events_pthread_is_active = false;
}
}
#endif
@@ -1579,9 +1597,11 @@ static void gwl_display_destroy(GWL_Display *display)
#endif
#ifdef USE_EVENT_BACKGROUND_THREAD
if (display->events_pthread) {
gwl_display_event_thread_destroy(display);
display->system->server_mutex->unlock();
if (!display->background) {
if (display->events_pthread) {
gwl_display_event_thread_destroy(display);
display->system->server_mutex->unlock();
}
}
/* Important to remove after the seats which may have key repeat timers active. */
@@ -7335,6 +7355,7 @@ static const wl_registry_listener registry_listener = {
static void *gwl_display_event_thread_fn(void *display_voidp)
{
GWL_Display *display = static_cast<GWL_Display *>(display_voidp);
GHOST_ASSERT(!display->background, "Foreground only");
const int fd = wl_display_get_fd(display->wl.display);
while (display->events_pthread_is_active) {
/* Wait for an event, this thread is dedicated to event handling. */
@@ -7357,6 +7378,7 @@ static void *gwl_display_event_thread_fn(void *display_voidp)
/* Event reading thread. */
static void gwl_display_event_thread_create(GWL_Display *display)
{
GHOST_ASSERT(!display->background, "Foreground only");
GHOST_ASSERT(display->events_pthread == 0, "Only call once");
display->events_pending.reserve(events_pending_default_size);
display->events_pthread_is_active = true;
@@ -7369,6 +7391,7 @@ static void gwl_display_event_thread_create(GWL_Display *display)
static void gwl_display_event_thread_destroy(GWL_Display *display)
{
GHOST_ASSERT(!display->background, "Foreground only");
pthread_cancel(display->events_pthread);
}
@@ -7395,7 +7418,9 @@ GHOST_SystemWayland::GHOST_SystemWayland(bool background)
ghost_wayland_log_handler);
display_->system = this;
display_->background = background;
/* Connect to the Wayland server. */
display_->wl.display = wl_display_connect(nullptr);
if (!display_->wl.display) {
display_destroy_and_free_all();
@@ -7506,8 +7531,16 @@ GHOST_SystemWayland::GHOST_SystemWayland(bool background)
wl_display_roundtrip(display_->wl.display);
#ifdef USE_EVENT_BACKGROUND_THREAD
gwl_display_event_thread_create(display_);
/* There is no need for an event handling thread in background mode
* because there no polling for user input. */
if (background) {
GHOST_ASSERT(display_->events_pthread_is_active == false, "Expected to be false");
}
else {
gwl_display_event_thread_create(display_);
}
/* Could be null in background mode, however there are enough
* references to this that it's safer to create it. */
display_->ghost_timer_manager = new GHOST_TimerManager();
#endif
}
@@ -7556,7 +7589,7 @@ bool GHOST_SystemWayland::processEvents(bool waitForEvent)
}
}
{
if (!display_->background) {
std::lock_guard lock{display_->events_pending_mutex};
for (const GHOST_IEvent *event : display_->events_pending) {
@@ -9230,6 +9263,7 @@ uint64_t GHOST_SystemWayland::ms_from_input_time(const uint32_t timestamp_as_uin
GHOST_TSuccess GHOST_SystemWayland::pushEvent_maybe_pending(const GHOST_IEvent *event)
{
#ifdef USE_EVENT_BACKGROUND_THREAD
GHOST_ASSERT(!display_->background, "Foreground only");
if (main_thread_id != std::this_thread::get_id()) {
std::lock_guard lock{display_->events_pending_mutex};
display_->events_pending.push_back(event);