Details
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Bug
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Resolution: Unresolved
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P1: Critical
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5.15.15, 6.6.2, 6.8.2
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None
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Linux/Wayland
Description
The following code, when run, will cause a segfault:
#include <QCoreApplication> #include <QJSEngine> #include <QDebug> int main(int argc, char **argv) { QCoreApplication app(argc, argv); QJSEngine myEngine; QJSValue fun = myEngine.globalObject().property("eval"); QJSValue ret = fun.call({ "99" }); qDebug() << ret.toString(); return 0; }
The following GDB session shows backtrace, as well as showing what variable is null.
(gdb) r Starting program: /home/peat/Development/QtRN/QtRN/toy/toy-qt6 [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".Program received signal SIGSEGV, Segmentation fault. QV4::EvalFunction::evalCall (argc=<optimized out>, directCall=false, argv=0x7ffff2bbf4f0, this=0x7ffff7fba040) at /usr/src/qt6-declarative-6.6.2+dfsg-4/src/qml/jsruntime/qv4globalobject.cpp:307 warning: 307 /usr/src/qt6-declarative-6.6.2+dfsg-4/src/qml/jsruntime/qv4globalobject.cpp: No such file or directory (gdb) bt #0 QV4::EvalFunction::evalCall (argc=<optimized out>, directCall=false, argv=0x7ffff2bbf4f0, this=0x7ffff7fba040) at /usr/src/qt6-declarative-6.6.2+dfsg-4/src/qml/jsruntime/qv4globalobject.cpp:307 #1 QV4::EvalFunction::evalCall (this=0x7ffff7fba040, argv=0x7ffff2bbf4f0, argc=1, directCall=false) at /usr/src/qt6-declarative-6.6.2+dfsg-4/src/qml/jsruntime/qv4globalobject.cpp:301 #2 0x00007ffff7b609e4 in QV4::FunctionObject::call (argc=1, argv=0x7ffff2bbf4f0, thisObject=0x7ffff2bbf4e8, this=0x7ffff7fba040) at /usr/src/qt6-declarative-6.6.2+dfsg-4/src/qml/jsruntime/qv4functionobject_p.h:171 #3 QV4::FunctionObject::call (data=<optimized out>, this=0x7ffff7fba040) at /usr/src/qt6-declarative-6.6.2+dfsg-4/src/qml/jsruntime/qv4jscall_p.h:93 #4 QJSValue::call (this=<optimized out>, args=...) at /usr/src/qt6-declarative-6.6.2+dfsg-4/src/qml/jsapi/qjsvalue.cpp:707 #5 0x0000555555555543 in main () (gdb) print v4->currentStackFrame $1 = (QV4::CppStackFrame *) 0x0
I currently workaround this by monkey-patching `eval` in global object to be an ordinary function which subsequently call real `eval`, like this:
myEngine.evaluate(QStringLiteral(
"(function () {"
" const realEval = eval;"
" eval = function (s) { return realEval(s); };"
"})()"
));
This affects both Qt 5 and Qt 6.