Buffer overflow in the VFAT filesystem implementation in the Linux kernel
before 3.3 allows local users to gain privileges or cause a denial of
service (system crash) via a VFAT write operation on a filesystem with the
utf8 mount option, which is not properly handled during UTF-8 to UTF-16
conversion.

A flaw was discovered on the Linux kernel's VFAT filesystem driver when a
disk is mounted with the utf8 option (this is the default on Ubuntu). On a
system where disks/images can be auto-mounted or a FAT filesystem is
mounted an unprivileged user can exploit the flaw to gain root privileges.