kdelibs4: preventing a crash in the KWindowInfo::Private destructor

[RJVB (René Bertin)]

I came across a bug, as reported in my rekonq port submission: the snippet

             Q_FOREACH(const QWeakPointer<RekonqWindow> &pointer, wList)
             {
                 if (KWindowInfo(pointer.data()->effectiveWinId(), NET::WMDesktop, 0).isOnCurrentDesktop())
                     return pointer.data();
             }

will lead to calling CFRelease with a NULL argument in KWindowInfo::Private::~Private(). Cocoa allows sending a message (like release) to a nil object, but the CoreFoundation version CFRelease will crash when passed a NULL pointer. This is confirmed by the API documentation.

Attached is a very simple patch that adds the required check before calling CFRelease - as is done all other times that function is called.

[ryandesign (Ryan Carsten Schmidt)]

You should also attach a patch for the portfile. The portfile's revision would need to be increased.

[NicosPavlov]

I am currently trying to clean up the various patches of kdelibs4, so I will surely consider this one when committing. However, considering the type of issue, it should really be reported upstream.

[RJVB (René Bertin)]

I am currently trying to clean up the various patches of kdelibs4, so I will surely consider this one when committing. However, considering the type of issue, it should really be reported upstream.

Has been done, but against 4.13.x because it's still there. Patching older versions is probably up to those still using them as I doubt we'll see a 4.12.6 release!

[NicosPavlov]

In that case, providing the link to ease tracking could prove useful:

​https://bugs.kde.org/show_bug.cgi?id=337154

[mkae (Marko Käning)]

BTW, on our ​KDE ticket wiki page we've listed this in section ​Issues at ​KDE's bug tracker as an existing ​ticket at b.k.o. (334827) which I have marked as a duplicate just now.

[NicosPavlov]

Committed in r122038. Thanks for the submission.