From 12bc039baa2672c98518277ea146bedec3a92ac0 Mon Sep 17 00:00:00 2001 From: Lars Knoll Date: Thu, 21 Mar 2019 13:03:21 +0100 Subject: [PATCH] Don't iterate over the connections without holding a lock When checking whether a slot is connected to a signal, we need to hold the signalSlotLock to be sure about the answer, or we can get crashes when a connection gets removed while doing the check. The check in activate() can handle some uncertainty as it's only a shortcut to the longer path. Fixes: QTBUG-74604 Change-Id: I3fc822455fbadc0223ef68632f5fb3df3ff3e86d Reviewed-by: Aapo Keskimolo --- src/corelib/kernel/qobject.cpp | 18 +++++++++++++++++- src/corelib/kernel/qobject_p.h | 1 + 2 files changed, 18 insertions(+), 1 deletion(-) diff --git a/src/corelib/kernel/qobject.cpp b/src/corelib/kernel/qobject.cpp index 759ccaacd8..268f3949fd 100644 --- a/src/corelib/kernel/qobject.cpp +++ b/src/corelib/kernel/qobject.cpp @@ -415,6 +415,22 @@ bool QObjectPrivate::isSignalConnected(uint signalIndex, bool checkDeclarative) return false; } +bool QObjectPrivate::maybeSignalConnected(uint signalIndex) const +{ + ConnectionData *cd = connections.load(); + if (!cd) + return false; + + if (cd->allsignals.first) + return true; + + if (signalIndex < uint(cd->signalVector.count())) { + const QObjectPrivate::Connection *c = cd->signalVector.at(signalIndex).first; + return c != nullptr; + } + return false; +} + /*! \internal @@ -3599,7 +3615,7 @@ void doActivate(QObject *sender, int signal_index, void **argv) if (!argv) argv = empty_argv; - if (!sp->isSignalConnected(signal_index, false)) { + if (!sp->maybeSignalConnected(signal_index)) { // The possible declarative connection is done, and nothing else is connected if (callbacks_enabled && signal_spy_set->signal_begin_callback != nullptr) signal_spy_set->signal_begin_callback(sender, signal_index, argv); diff --git a/src/corelib/kernel/qobject_p.h b/src/corelib/kernel/qobject_p.h index 823c7a195a..863689fddd 100644 --- a/src/corelib/kernel/qobject_p.h +++ b/src/corelib/kernel/qobject_p.h @@ -254,6 +254,7 @@ public: int signalIndex(const char *signalName, const QMetaObject **meta = nullptr) const; bool isSignalConnected(uint signalIdx, bool checkDeclarative = true) const; + bool maybeSignalConnected(uint signalIndex) const; inline bool isDeclarativeSignalConnected(uint signalIdx) const; // To allow abitrary objects to call connectNotify()/disconnectNotify() without making