VM crashes often on USB unplug/replug, also out of blue sky

[ucrasher2]

Hi, this looks like a regression in 6.1.2 and 6.0.16 since I cannot duplicate with 6.0.14. The VM simply disappears from the screen. Sometimes with no visible reason, but every few USB unplug/replug cycles. I found the USB part since I write some code that communicates to a USB device (CDC-ACM aka ComPort emulation). One of the actions does cause the device to reboot (on purpose).

Other times it sits in the background and when I want to open the VM window again, it is gone. Then sometimes it crashes immediately at start or shortly after. A host reboot brings it back to work (until it crashes randomly again). Host and guest are running with latest updates. H: Ubuntu 18.04, 5.3.0-40-generic G: Win10-64, 19H2 (but also showed at 19h1)

I have not seen a crash with Linux guests, but do not use them often right now.

In the logs I did not find useful hints, I hope you do. Let me know when I can help with debugging.

There is a thread in the forum: ​https://forums.virtualbox.org/viewtopic.php?f=7&t=96829&p=470373#p470373

[ucrasher2]

6.0.16 crash at USB replug

[ucrasher2]

6.1.2 crash out of blue sky

[ucrasher2]

Today I've got another crash after 2 weeks of silence. This time it is happened even with V6.0.14. On the syslog there is a segfault listed and the trigger was USB plug-in.

See 2020-03-04USB_unplug_VB6.0.14.zip

[ucrasher2]

6.0.14 segfault at USB plug-in