The d_walk function in fs/dcache.c in the Linux kernel through 3.17.2 does not properly maintain the semantics of rename_lock, which allows local users to cause a denial of service (deadlock and system hang) via a crafted application.
https://support.f5.com/csp/article/K05211147
https://lkml.org/lkml/2014/10/26/129
https://lkml.org/lkml/2014/10/26/128
https://lkml.org/lkml/2014/10/26/101
https://lkml.org/lkml/2014/10/25/180
https://lkml.org/lkml/2014/10/25/179
https://bugzilla.redhat.com/show_bug.cgi?id=1159313
http://www.ubuntu.com/usn/USN-2518-1
http://www.ubuntu.com/usn/USN-2517-1
http://www.ubuntu.com/usn/USN-2516-1
http://www.ubuntu.com/usn/USN-2515-1
http://www.ubuntu.com/usn/USN-2493-1
http://www.ubuntu.com/usn/USN-2492-1
http://www.securitytracker.com/id/1034051
http://www.securityfocus.com/bid/70854
http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html
http://www.openwall.com/lists/oss-security/2014/10/30/7
http://rhn.redhat.com/errata/RHSA-2015-1978.html
http://rhn.redhat.com/errata/RHSA-2015-1976.html
http://lists.opensuse.org/opensuse-security-announce/2015-04/msg00015.html
http://lists.opensuse.org/opensuse-security-announce/2015-04/msg00009.html
http://lists.opensuse.org/opensuse-security-announce/2015-03/msg00025.html
http://lists.opensuse.org/opensuse-security-announce/2015-03/msg00020.html
http://lists.opensuse.org/opensuse-security-announce/2015-03/msg00010.html
http://lists.opensuse.org/opensuse-security-announce/2015-01/msg00035.html