arch/ia64/xen/faults.c in Xen 3.4 and 4.0 in Linux kernel 2.6.18, and possibly other kernel versions, when running on IA-64 architectures, allows local users to cause a denial of service and "turn on BE by modifying the user mask of the PSR," as demonstrated via exploitation of CVE-2006-0742.
https://exchange.xforce.ibmcloud.com/vulnerabilities/59373
https://bugzilla.redhat.com/show_bug.cgi?id=586415
http://xenbits.xensource.com/xen-4.0-testing.hg?rev/42caadb14edb
http://www.vmware.com/security/advisories/VMSA-2011-0003.html
http://www.securityfocus.com/bid/40776
http://www.securityfocus.com/archive/1/516397/100/0/threaded
http://www.redhat.com/support/errata/RHSA-2010-0610.html
http://www.openwall.com/lists/oss-security/2010/06/10/2