The journal_unmap_buffer function in fs/jbd2/transaction.c in the Linux kernel before 3.3.1 does not properly handle the _Delay and _Unwritten buffer head states, which allows local users to cause a denial of service (system crash) by leveraging the presence of an ext4 filesystem that was mounted with a journal.
Exploitability
AV:LAC:LAu:NImpact
C:NI:NA:C4.9/AV:L/AC:L/Au:N/C:N/I:N/A:C