(1) TMEMC_SAVE_GET_CLIENT_WEIGHT, (2) TMEMC_SAVE_GET_CLIENT_CAP, (3) TMEMC_SAVE_GET_CLIENT_FLAGS and (4) TMEMC_SAVE_END in the Transcendent Memory (TMEM) in Xen 4.0, 4.1, and 4.2 allow local guest OS users to cause a denial of service (NULL pointer dereference or memory corruption and host crash) or possibly have other unspecified impacts via a NULL client id.
https://security.gentoo.org/glsa/201604-03
https://exchange.xforce.ibmcloud.com/vulnerabilities/78268
http://www.securitytracker.com/id?1027482
http://www.securityfocus.com/bid/55410
http://www.openwall.com/lists/oss-security/2012/09/05/8
http://wiki.xen.org/wiki/Security_Announcements#XSA-15_multiple_TMEM_hypercall_vulnerabilities
http://security.gentoo.org/glsa/glsa-201309-24.xml
http://secunia.com/advisories/55082
http://secunia.com/advisories/51413
http://secunia.com/advisories/51352
http://secunia.com/advisories/51324
http://secunia.com/advisories/50472
http://lists.xen.org/archives/html/xen-announce/2012-09/msg00006.html
http://lists.opensuse.org/opensuse-security-announce/2014-03/msg00021.html
http://lists.opensuse.org/opensuse-security-announce/2012-11/msg00018.html
http://lists.opensuse.org/opensuse-security-announce/2012-11/msg00017.html
http://lists.opensuse.org/opensuse-security-announce/2012-11/msg00009.html
http://lists.opensuse.org/opensuse-security-announce/2012-11/msg00008.html