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  1. Qt
  2. QTBUG-127027

paintDevice used after QBackingStore::endPaint()

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Details

    • Bug
    • Resolution: Fixed
    • P1: Critical
    • 6.7.3, 6.8
    • 6.7.0
    • Quick: SceneGraph
    • None
    • Linux/Other display system
    • 6e732bc72e9e710e6b2c2c2b3a9ccb9c9aed8150

    Description

      reproduce steps (crash kwin_wayland)

      step 1

      download neon-developer-20240701-1630.iso

      step 2

      boot neon-developer-20240701-1630.iso in virtual machine

      qemu-system-x86_64 -vga virtio -m 2048 -cdrom /path/to/neon-developer-20240701-1630.iso

      step 3

      open konsole and run

      mkdir -p ~/.config/plasma-workspace/env
echo 'export KWIN_COMPOSE=Q' > ~/.config/plasma-workspace/env/kwin.sh

      step 4

      log out and wait for automatic log in

      step 5

      drag "Welcome Center" window to left edge of screen and kwin_wayland should crash

      I think bug is in libQt6Quick.so.6.7.0 and not kwin_wayland because I found code that uses pointer returned from QBackingStore::paintDevice() after QBackingStore::endPaint(): https://github.com/qt/qtdeclarative/blob/5d52461f80e9f261e43c05e0be452a9534bcc9ab/src/quick/scenegraph/adaptations/software/qsgsoftwarerenderer.cpp#L68-L80

      https://doc.qt.io/qt-6/qbackingstore.html#paintDevice

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            vgt Eirik Aavitsland
            bzzzz BZZZZ DZZZZ
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            Dates

              Created:
              Updated:
              Resolved:

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