On Fri Jun 17, 2022 at 10:06:01AM +0200, Theo Buehler wrote:
> The patch below is a hack that makes qgis build on aarch64. It's
> not the correct fix.
>
> What happens is that the destructor of the QWaitCondition class is
> called more than once.
IMHO The issue is the python code or in other words where it is used.
> The second time it is called from Python's atexit
> handler crashes due to a use-after-free in pthread_cond_destroy().
>
> The patch below simply avoids this. The correct fix would have to root
> cause why this happens on aarch64 and not on amd64.
There is no issue in Qt5 or QWaitCondition itself. I'm fine with the
patch but please add a comment and a referent to qgis / x11/py-qt5
please.
Thanks Rafael
>
> The backtrace looks something like this:
>
> Program terminated with signal SIGSEGV, Segmentation fault.
> #0 pthread_cond_destroy (condp=0x8) at
> /usr/src/lib/libc/thread/rthread_cond.c:54
> 54 cond = *condp;
> (gdb) bt
> #0 pthread_cond_destroy (condp=0x8) at
> /usr/src/lib/libc/thread/rthread_cond.c:54
> #1 0x00000017eee75c94 in QWaitCondition::~QWaitCondition() ()
> from /usr/local/lib/qt5/libQt5Core.so.3.0
> #2 0x000000187be1cbf0 in _libc___cxa_finalize (dso=0x0) at
> /usr/src/lib/libc/stdlib/atexit.c:177
> #3 0x000000187be04f60 in _libc_exit (status=0) at
> /usr/src/lib/libc/stdlib/exit.c:54
> #4 0x000000184b7b79cc in Py_Exit () from /usr/local/lib/libpython3.9.so.0.0
> #5 0x000000184b7bd0d0 in _PyErr_PrintEx () from
> /usr/local/lib/libpython3.9.so.0.0
> #6 0x000000184b7bbdfc in PyRun_SimpleFileExFlags () from
> /usr/local/lib/libpython3.9.so.0.0
> #7 0x000000184b7e0bec in Py_RunMain () from
> /usr/local/lib/libpython3.9.so.0.0
> #8 0x000000184b7e1bdc in pymain_main () from
> /usr/local/lib/libpython3.9.so.0.0
> #9 0x000000184b7e1ed8 in Py_BytesMain () from
> /usr/local/lib/libpython3.9.so.0.0
> #10 0x00000013a6600860 in _start ()
>
> Index: Makefile
> ===================================================================
> RCS file: /cvs/ports/x11/qt5/qtbase/Makefile,v
> retrieving revision 1.52
> diff -u -p -r1.52 Makefile
> --- Makefile 11 Mar 2022 20:16:59 -0000 1.52
> +++ Makefile 17 Jun 2022 07:47:27 -0000
> @@ -7,7 +7,7 @@ COMMENT-mysql = MySQL plugin for Qt5
> COMMENT-psql = PostgresSQL plugin for Qt5
> COMMENT-tds = TDS plugin for Qt5
>
> -REVISION-main = 9
> +REVISION-main = 10
> REVISION-examples = 0
>
> PKGNAME-mysql = qt5-mysql-${VERSION}
> Index: patches/patch-src_corelib_thread_qwaitcondition_unix_cpp
> ===================================================================
> RCS file: patches/patch-src_corelib_thread_qwaitcondition_unix_cpp
> diff -N patches/patch-src_corelib_thread_qwaitcondition_unix_cpp
> --- /dev/null 1 Jan 1970 00:00:00 -0000
> +++ patches/patch-src_corelib_thread_qwaitcondition_unix_cpp 17 Jun 2022
> 06:46:24 -0000
> @@ -0,0 +1,16 @@
> +Index: src/corelib/thread/qwaitcondition_unix.cpp
> +--- src/corelib/thread/qwaitcondition_unix.cpp.orig
> ++++ src/corelib/thread/qwaitcondition_unix.cpp
> +@@ -181,9 +181,12 @@ QWaitCondition::QWaitCondition()
> +
> + QWaitCondition::~QWaitCondition()
> + {
> ++ if (d == nullptr)
> ++ return;
> + report_error(pthread_cond_destroy(&d->cond), "QWaitCondition", "cv
> destroy");
> + report_error(pthread_mutex_destroy(&d->mutex), "QWaitCondition", "mutex
> destroy");
> + delete d;
> ++ d = nullptr;
> + }
> +
> + void QWaitCondition::wakeOne()
>
