[REG 6.5 -> 6.8] Crashes in QQmlTypeLoader threads / QQmlPropertyCache::toMetaObjectBuilder()

We recently upgraded our Windows/Android app from Qt 6.5.6 to 6.8.0 and are since seeing various crashes in QQmlTypeLoader threads at app launch, the most common one of which occurs in QQmlPropertyCache::toMetaObjectBuilder():

• Android: QQmlPropertyCache::toMetaObjectBuilder()
• Windows: QQmlPropertyCache::toMetaObjectBuilder()

(All stack traces show relative addresses to the official Qt 6.8.0 pre-built libraries.)

Some of the crashes have associated GWP-ASan info like this in Google Play:

[GWP-ASan]: Buffer Overflow, 6 bytes right of a 39-byte allocation at 0x739f617fd8

Here are some of these crashes, which are also attached with the ASan info included:

• QQmlPropertyCache::signalParameterNames()
• QQmlImports::resolveType()

There are many other similar stack traces occurring on Android, all of them involving QQmlTypeLoader and on background threads started from QThread::exec(). I’m not entirely sure if they have the same root cause as the crashes in QQmlPropertyCache linked above, but they seemed similar enough to mention them here together. They might only be happening on Android due to GWP-ASan being active there.

Unfortunately we’re unable to reproduce any of these issues, but I’m hoping that the provided info can give a lead. Please let me know if I can provide any further info.