1 files changed, 162 insertions, 0 deletions
diff --git a/kde-plasma/kwin/files/kwin-5.19.5-safe-removal-of-X11-event-filters.patch b/kde-plasma/kwin/files/kwin-5.19.5-safe-removal-of-X11-event-filters.patch
new file mode 100644
index 000000000000..7eeccf6e8c5f
--- /dev/null
+++ b/kde-plasma/kwin/files/kwin-5.19.5-safe-removal-of-X11-event-filters.patch
@@ -0,0 +1,162 @@
+From c5880833d94330d022c4b6fc84c175aadeaf9632 Mon Sep 17 00:00:00 2001
+From: Vlad Zahorodnii <vlad.zahorodnii@kde.org>
+Date: Tue, 22 Sep 2020 08:53:17 +0000
+Subject: [PATCH] x11: Make removal of X11 event filters safe
+
+If an X11 event filter has been activated and it unregisters another X11
+event filter, then the window manager may crash because the foreach macro
+in Workspace::workspaceEvent() makes a copy of m_genericEventFilters or
+m_eventFilters and we can call the event() method for an already defunct
+filter.
+
+With this change, X11 event filters can be safely removed and installed
+at any particular moment.
+
+BUG: 423319
+
+
+(cherry picked from commit a433fb08a3a9255802405a17dd4c8270c68fcb25)
+---
+ events.cpp    | 52 +++++++++++++++++++++++++++++++++++++++++----------
+ workspace.cpp | 10 ++++++++++
+ workspace.h   | 17 +++++++++++++++--
+ 3 files changed, 67 insertions(+), 12 deletions(-)
+
+diff --git a/events.cpp b/events.cpp
+index eb3572d13..2e8885d76 100644
+--- a/events.cpp
++++ b/events.cpp
+@@ -165,18 +165,34 @@ QVector<QByteArray> s_xcbEerrors({
+ 
+ void Workspace::registerEventFilter(X11EventFilter *filter)
+ {
+-    if (filter->isGenericEvent())
+-        m_genericEventFilters.append(filter);
+-    else
+-        m_eventFilters.append(filter);
++    if (filter->isGenericEvent()) {
++        m_genericEventFilters.append(new X11EventFilterContainer(filter));
++    } else {
++        m_eventFilters.append(new X11EventFilterContainer(filter));
++    }
++}
++
++static X11EventFilterContainer *takeEventFilter(X11EventFilter *eventFilter,
++                                                QList<QPointer<X11EventFilterContainer>> &list)
++{
++    for (int i = 0; i < list.count(); ++i) {
++        X11EventFilterContainer *container = list.at(i);
++        if (container->filter() == eventFilter) {
++            return list.takeAt(i);
++        }
++    }
++    return nullptr;
+ }
+ 
+ void Workspace::unregisterEventFilter(X11EventFilter *filter)
+ {
+-    if (filter->isGenericEvent())
+-        m_genericEventFilters.removeOne(filter);
+-    else
+-        m_eventFilters.removeOne(filter);
++    X11EventFilterContainer *container = nullptr;
++    if (filter->isGenericEvent()) {
++        container = takeEventFilter(filter, m_genericEventFilters);
++    } else {
++        container = takeEventFilter(filter, m_eventFilters);
++    }
++    delete container;
+ }
+ 
+ 
+@@ -219,13 +235,29 @@ bool Workspace::workspaceEvent(xcb_generic_event_t *e)
+     if (eventType == XCB_GE_GENERIC) {
+         xcb_ge_generic_event_t *ge = reinterpret_cast<xcb_ge_generic_event_t *>(e);
+ 
+-        foreach (X11EventFilter *filter, m_genericEventFilters) {
++        // We need to make a shadow copy of the event filter list because an activated event
++        // filter may mutate it by removing or installing another event filter.
++        const auto eventFilters = m_genericEventFilters;
++
++        for (X11EventFilterContainer *container : eventFilters) {
++            if (!container) {
++                continue;
++            }
++            X11EventFilter *filter = container->filter();
+             if (filter->extension() == ge->extension && filter->genericEventTypes().contains(ge->event_type) && filter->event(e)) {
+                 return true;
+             }
+         }
+     } else {
+-        foreach (X11EventFilter *filter, m_eventFilters) {
++        // We need to make a shadow copy of the event filter list because an activated event
++        // filter may mutate it by removing or installing another event filter.
++        const auto eventFilters = m_eventFilters;
++
++        for (X11EventFilterContainer *container : eventFilters) {
++            if (!container) {
++                continue;
++            }
++            X11EventFilter *filter = container->filter();
+             if (filter->eventTypes().contains(eventType) && filter->event(e)) {
+                 return true;
+             }
+diff --git a/workspace.cpp b/workspace.cpp
+index a87a622e9..fd3634b16 100644
+--- a/workspace.cpp
++++ b/workspace.cpp
+@@ -66,6 +66,16 @@ namespace KWin
+ extern int screen_number;
+ extern bool is_multihead;
+ 
++X11EventFilterContainer::X11EventFilterContainer(X11EventFilter *filter)
++    : m_filter(filter)
++{
++}
++
++X11EventFilter *X11EventFilterContainer::filter() const
++{
++    return m_filter;
++}
++
+ ColorMapper::ColorMapper(QObject *parent)
+     : QObject(parent)
+     , m_default(kwinApp()->x11DefaultScreen()->default_colormap)
+diff --git a/workspace.h b/workspace.h
+index 489d7bae4..61fb215a8 100644
+--- a/workspace.h
++++ b/workspace.h
+@@ -55,6 +55,19 @@ class X11Client;
+ class X11EventFilter;
+ enum class Predicate;
+ 
++class X11EventFilterContainer : public QObject
++{
++    Q_OBJECT
++
++public:
++    explicit X11EventFilterContainer(X11EventFilter *filter);
++
++    X11EventFilter *filter() const;
++
++private:
++    X11EventFilter *m_filter;
++};
++
+ class KWIN_EXPORT Workspace : public QObject
+ {
+     Q_OBJECT
+@@ -654,8 +667,8 @@ private:
+ 
+     QScopedPointer<KillWindow> m_windowKiller;
+ 
+-    QList<X11EventFilter *> m_eventFilters;
+-    QList<X11EventFilter *> m_genericEventFilters;
++    QList<QPointer<X11EventFilterContainer>> m_eventFilters;
++    QList<QPointer<X11EventFilterContainer>> m_genericEventFilters;
+     QScopedPointer<X11EventFilter> m_movingClientFilter;
+     QScopedPointer<X11EventFilter> m_syncAlarmFilter;
+ 
+-- 
+GitLab
+