Keep Qt's own message dialogs on Plasma (fixes SIGSEGV in ~QMessageBox) - #69
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Keep Qt's own message dialogs on Plasma (fixes SIGSEGV in ~QMessageBox)#69wehrwolfmann wants to merge 1 commit into
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On Plasma our message boxes go through KDEPlatformMessageDialogHelper. It creates its own QMessageBox, sets Qt::WA_DeleteOnClose on it and keeps a raw pointer to it. QDialog::exec() deletes that dialog when it closes, so the helper is left with a dangling pointer; the later hide() call from ~QMessageBox dereferences freed memory and kills the app with SIGSEGV. The defect is in plasma-integration, but every QMessageBox in the app is exposed to it, so keep Qt's own dialogs instead. Nothing changes visually - the "native" Plasma dialog is a QMessageBox as well. Measured with the patch: 10 About/License cycles under a debugger, zero helper dialogs created and zero setNativeDialogVisible calls. Without it the helper dialog is created and destroyed before our own box on every click.
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Fixes #68 — the analysis and the core-dump frames are there.
Short version: on Plasma
KDEPlatformMessageDialogHelpercreates its ownQMessageBox, setsQt::WA_DeleteOnCloseon it and keeps a raw pointer.QDialog::exec()deletes that dialog when it closes, so the helper is left with a dangling pointer, and thehide()call from~QMessageBoxwalks into freed memory.The real defect is in plasma-integration and I am reporting it there as well, but every
QMessageBoxin this app is exposed to it, so this one line keeps Qt's own dialogs. Nothing changes visually — the "native" Plasma dialog is aQMessageBoxtoo.Measured: with the patch, 10 About/License cycles under a debugger produce zero helper dialogs and zero
setNativeDialogVisiblecalls, app alive. Without it the helper dialog is created and destroyed before the app's own box on every single About click.