The _xfs_buf_find function in fs/xfs/xfs_buf.c in the Linux kernel before 3.7.6 does not validate block numbers, which allows local users to cause a denial of service (NULL pointer dereference and system crash) or possibly have unspecified other impact by leveraging the ability to mount an XFS filesystem containing a metadata inode with an invalid extent map.
https://github.com/torvalds/linux/commit/eb178619f930fa2ba2348de332a1ff1c66a31424
https://bugzilla.redhat.com/show_bug.cgi?id=918009
http://www.ubuntu.com/usn/USN-1975-1
http://www.ubuntu.com/usn/USN-1973-1
http://www.ubuntu.com/usn/USN-1972-1
http://www.ubuntu.com/usn/USN-1970-1
http://www.ubuntu.com/usn/USN-1969-1
http://www.ubuntu.com/usn/USN-1968-1
http://www.openwall.com/lists/oss-security/2013/03/05/10
http://www.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.7.6
http://lists.opensuse.org/opensuse-updates/2013-12/msg00129.html
http://lists.opensuse.org/opensuse-security-announce/2013-09/msg00004.html
http://lists.opensuse.org/opensuse-security-announce/2013-09/msg00003.html