The shmem_delete_inode function in mm/shmem.c in the tmpfs implementation in the Linux kernel before 2.6.26.1 allows local users to cause a denial of service (system crash) via a certain sequence of file create, remove, and overwrite operations, as demonstrated by the insserv program, related to allocation of "useless pages" and improper maintenance of the i_blocks count.
http://lkml.org/lkml/2008/7/26/71
http://secunia.com/advisories/31881
http://secunia.com/advisories/32190
http://secunia.com/advisories/32393
http://www.debian.org/security/2008/dsa-1636
http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.26.1
http://www.redhat.com/support/errata/RHSA-2008-0857.html
http://www.securityfocus.com/bid/31134