V4 crash if executing a Qt Quick test without /proc mounted

[Timo Jyrinki]

The ubuntu-ui-toolkit test segfaults (bug #1266707 etc) may be because V4 engine seems to crash if /proc is not mounted. I noticed this when building in a chroot environment with and without /proc mounted.

Just executing './tst_components -platform minimal' in ubuntu-ui-toolkit/tests/unit/tst_components crashes as follows:

#0 __GI___libc_free (mem=0x18) at malloc.c:2888
#1 0x00007ffff4ed3cfd in __pthread_attr_destroy (attr=<optimized out>) at pthread_attr_destroy.c:41
#2 0x00007ffff579ed86 in QV4::MemoryManager::MemoryManager() () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#3 0x00007ffff57843bc in QV4::ExecutionEngine::ExecutionEngine(QQmlJS::EvalISelFactory*) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#4 0x00007ffff59021f2 in QV8Engine::QV8Engine(QJSEngine*) () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#5 0x00007ffff577f294 in QJSEngine::QJSEngine(QJSEnginePrivate&, QObject*) () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#6 0x00007ffff5834170 in QQmlEngine::QQmlEngine(QObject*) () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#7 0x00007ffff5e95298 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#8 0x00007ffff7bc7689 in quick_test_main(int, char**, char const*, char const*) ()
   from /usr/lib/x86_64-linux-gnu/libQt5QuickTest.so.5
#9 0x00007ffff7816ed5 in __libc_start_main (main=0x4005d0 <main(int, char**)>, argc=3, argv=0x7fffffffe598, init=<optimized out>,
    fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffe588) at libc-start.c:287
#10 0x000000000040060c in _start ()

And it does not crash if /proc is mounted.

This is when using Qt 5.2 from ppa:canonical-qt5-edgers/qt5-beta2

[Albert Astals Cid (aacid)]

See https://codereview.qt-project.org/#change,75282

[Timo Jyrinki (timo-jyrinki)]

Looking at: https://launchpad.net/~canonical-qt5-edgers/+archive/qt5-beta2/+builds?build_text=ubuntu-ui-toolkit&build_state=all

The '1:0.1.46+14.04.20131216-0~913+201401130534~ubuntu14.04.1' x86 rebuild attemps were made after qtdeclarative with the fix was already there in the PPA and used according to logs (~test5 version). The PPA test failure did not change before/after the qtdeclarative change.

armhf seemed to succeed because of some other reason, because at that time the qtdeclarative was unchanged.

The previous build to compare to is '1:0.1.46+14.04.20131216-0~907~ubuntu14.04.1', since the builds between failed because of libicu48 -> libicu52 transition which required recompilation of qtbase.

It seems this particular bug is fixed by the patch, but it does not resolve all of ubuntu-ui-toolkit's problems.

[Launchpad Janitor (janitor)]

This bug was fixed in the package qtdeclarative-opensource-src - 5.2.1-3ubuntu10

---------------
qtdeclarative-opensource-src (5.2.1-3ubuntu10) trusty; urgency=medium

  * debian/patches/Fix-crash-when-appending-arrays-to-sub-models-in-lis.patch
    - Backport from upstream https://codereview.qt-project.org/#change,80934
      (LP: #1291602)
 -- Timo Jyrinki <email address hidden> Fri, 14 Mar 2014 09:37:56 +0000