Various routines for the ppc64 architecture on Linux kernel 2.6 prior to 2.6.2 and 2.4 prior to 2.4.24 do not use the copy_from_user function when copying data from userspace to kernelspace, which crosses security boundaries and allows local users to cause a denial of service.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A9707
http://www.redhat.com/support/errata/RHSA-2004-017.html
http://linux.bkbits.net:8080/linux-2.6/cset%403ffcf122S7e3xPZCpibrXq6KRRjwqw
http://linux.bkbits.net:8080/linux-2.4/cset%403fdd54b3u9Eq0Wny2Nn1HGfI3pofOQ