The ohci_bus_start function in the USB OHCI emulation support (hw/usb/hcd-ohci.c) in QEMU allows local guest OS administrators to cause a denial of service (NULL pointer dereference and QEMU process crash) via vectors related to multiple eof_timers.
https://bugzilla.redhat.com/show_bug.cgi?id=1304794
https://lists.debian.org/debian-lts-announce/2018/11/msg00038.html
https://lists.gnu.org/archive/html/qemu-devel/2016-02/msg03374.html