The sys_add_key function in the keyring code in Linux kernel 2.6.16.1 and 2.6.17-rc1, and possibly earlier versions, allows local users to cause a denial of service (OOPS) via keyctl requests that add a key to a user key instead of a keyring key, which causes an invalid dereference in the __keyring_search_one function.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A9325
https://exchange.xforce.ibmcloud.com/vulnerabilities/25722
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=188466
http://www.vupen.com/english/advisories/2006/1475
http://www.vupen.com/english/advisories/2006/1307
http://www.ubuntu.com/usn/usn-302-1
http://www.securityfocus.com/bid/17451
http://www.redhat.com/support/errata/RHSA-2006-0493.html
http://www.mandriva.com/security/advisories?name=MDKSA-2006:086
http://support.avaya.com/elmodocs2/security/ASA-2006-161.htm
http://secunia.com/advisories/21745
http://secunia.com/advisories/20716
http://secunia.com/advisories/20237
http://secunia.com/advisories/20157
http://secunia.com/advisories/19735