Clicking on this ::marker in dev tools crashes the page

[Psychpsyo]

Summary

Just read the repro steps.

Operating system

Linux

Steps to reproduce

1. Open this page:

<style>
 foo { }
</style>
<li>

2. There's about a 50/50 chance that the <li> has a ::marker in the dev tools, and if it does, the page crashes when you click on it.

(also, that is a load-bearing style tag, without it the race condition doesn't happen)

Expected behavior

There should be a marker and clicking it in the dev tools should not crash the page.

Actual behavior

Only sometimes is there a marker and clicking it in the dev tools does crash the page.

URL for a reduced test case

data:text/html,<style>foo{}</style><li>

HTML/SVG/etc. source for a reduced test case

<style>
 foo { }
</style>
<li>

Log output and (if possible) backtrace

#0  ak_verification_failed ()
    at /home/tim/repos/ladybird/AK/Assertions.cpp:102
#1  0x00005d9d27037a74 in value ()
    at /home/tim/repos/ladybird/AK/Optional.h:478
#2  operator* () at /home/tim/repos/ladybird/AK/Optional.h:522
#3  0x00005d9d27037a74 in inspect_dom_node ()
#4  0x00005d9d27040faa in handle ()
    at Lagom/Services/WebContent/WebContentServerEndpoint.h:6066
#5  0x00007e4fea919c8b in handle_messages ()
    at /home/tim/repos/ladybird/Libraries/LibIPC/Connection.cpp:110
#6  0x00007e4fea8dbfcf in operator() ()
    at /home/tim/repos/ladybird/AK/Function.h:120
#7  0x00007e4fea8dbfcf in operator() ()
    at /home/tim/repos/ladybird/AK/Function.h:120
#8  0x00007e4fea8eb76b in process ()
    at /home/tim/repos/ladybird/Libraries/LibCore/ThreadEventQueue.cpp:118
#9  0x00007e4feb0739ef in event_target_received_event ()
    at /home/tim/repos/ladybird/Libraries/LibWebView/EventLoop/EventLoopImplementationQt.cpp:352
#10 0x00007e4feb075dec in WebView::EventLoopImplementationQtEventTarget::event(QEvent*) ()
    at /home/tim/repos/ladybird/Libraries/LibWebView/EventLoop/EventLoopImplementationQtEventTarget.cpp:14
#11 0x00007e4feab38416 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /lib/x86_64-linux-gnu/libQt6Core.so.6
#12 0x00007e4feab38635 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /lib/x86_64-linux-gnu/libQt6Core.so.6
#13 0x00007e4fead33a8f in ?? () from /lib/x86_64-linux-gnu/libQt6Core.so.6
#14 0x00007e4fe83145b5 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#15 0x00007e4fe8373717 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#16 0x00007e4fe8313a53 in g_main_context_iteration ()
   from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#17 0x00007e4fead315ef in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib/x86_64-linux-gnu/libQt6Core.so.6
#18 0x00007e4feab429a3 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib/x86_64-linux-gnu/libQt6Core.so.6
#19 0x00007e4fea8d9717 in exec ()
    at /home/tim/repos/ladybird/Libraries/LibCore/EventLoop.cpp:88
#20 0x00005d9d270308f1 in serenity_main ()
    at /home/tim/repos/ladybird/Services/WebContent/main.cpp:208
#21 0x00005d9d270eab52 in main ()
    at /home/tim/repos/ladybird/Libraries/LibMain/Main.cpp:39

Screenshots or screen recordings

Well, the page is completely white, even with ::marker.

Build flags or config settings

No response

Contribute a patch?

• I’ll contribute a patch for this myself.