The Linux kernel before 2.2.19 does not have unregister calls for (1) CPUID and (2) MSR drivers, which could cause a DoS (crash) by unloading and reloading the drivers.
https://www.debian.org/security/2001/dsa-047
http://www.redhat.com/support/errata/RHSA-2001-047.html
http://www.linux.org.uk/VERSION/relnotes.2219.html
http://marc.info/?l=bugtraq&m=99013830726309&w=2
http://marc.info/?l=bugtraq&m=98775114228203&w=2
http://marc.info/?l=bugtraq&m=98759029811377&w=2
http://marc.info/?l=bugtraq&m=98684172109474&w=2
http://marc.info/?l=bugtraq&m=98653252326445&w=2