The ext4_isize function in fs/ext4/ext4.h in the Linux kernel 2.6.27
before 188.8.131.52 and 2.6.28 before 184.108.40.206 uses the i_size_high
structure member during operations on arbitrary types of files, which
allows local users to cause a denial of service (CPU consumption and
error-message flood) by attempting to mount a crafted ext4 filesystem.