Bug#804758: libqt5widgets5: Crashes and drawing errors related to SHM

[Florian Bruhin <me@the-compiler.org>]

Package: libqt5widgets5
Version: 5.3.2+dfsg-4+deb8u1
Severity: normal

Dear Maintainer,

Since a few days, QtWebKit applications (such as Calibre or my minimal
PyQt test script[1]) crash when resizing the window. I think it mostly
happens when it's resized bigger than the window size when the
application was started.

Sometimes there's a segfault, sometimes just a warning printed:

    [...]
    QXcbShmImage: shmget() failed (28) for size 103376 (364x71)
    QXcbShmImage: shmget() failed (28) for size 905664 (636x356)
    QXcbShmImage: shmget() failed (28) for size 921600 (640x360)
    QXcbShmImage: shmget() failed (28) for size 8294400 (1920x1080)
    QXcbShmImage: shmget() failed (28) for size 8294400 (1920x1080)
    [...]

I also see drawing errors when using KeePassX (wich doesn't use
QtWebKit) with similar errors:

    QNativeImage: Unable to attach to shared memory segment. 
    X Error: BadDrawable (invalid Pixmap or Window parameter) 9
      Major opcode: 62 (X_CopyArea)
      Resource id:  0x0
    X Error: BadDrawable (invalid Pixmap or Window parameter) 9
      Major opcode: 62 (X_CopyArea)
      Resource id:  0x0

screenshot: http://the-compiler.org/tmp/qt5drawing.png

Everything non-Qt seems to work fine.

[1] https://github.com/The-Compiler/qutebrowser/blob/master/scripts/minimal_webkit_testbrowser.py

Florian

-- System Information:
Debian Release: 8.2
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 3.16.0-4-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages libqt5widgets5 depends on:
ii  libc6              2.19-18+deb8u1
ii  libglib2.0-0       2.42.1-1
ii  libqt5core5a       5.3.2+dfsg-4+deb8u1
ii  libqt5gui5         5.3.2+dfsg-4+deb8u1
ii  libstdc++6         4.9.2-10
ii  libx11-6           2:1.6.2-3
ii  multiarch-support  2.19-18+deb8u1

libqt5widgets5 recommends no packages.

libqt5widgets5 suggests no packages.

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