The cs_validate_page function in bsd/kern/ubc_subr.c in the xnu kernel 1228.0 and earlier in Apple Mac OS X 10.5.1 allows local users to cause a denial of service (failed assertion and system crash) via a crafted signed Mach-O binary that causes the hashes function to return NULL.
https://exchange.xforce.ibmcloud.com/vulnerabilities/38997
http://www.vupen.com/english/advisories/2008/1697
http://www.vupen.com/english/advisories/2007/4216
http://www.us-cert.gov/cas/techalerts/TA08-150A.html
http://secunia.com/advisories/30430
http://secunia.com/advisories/28048
http://lists.apple.com/archives/security-announce/2008//May/msg00001.html