The cifs_close function in fs/cifs/file.c in the Linux kernel before 2.6.39 allows local users to cause a denial of service (NULL pointer dereference and BUG) or possibly have unspecified other impact by setting the O_DIRECT flag during an attempt to open a file on a CIFS filesystem.
git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git%3Ba=commit%3Bh=7797069305d13252fd66cf722aa8f2cbeb3c95cd
marc.info/?l=linux-cifs&m=130204357001849&w=2
marc.info/?l=linux-cifs&m=130204730006155&w=2
securityreason.com/securityalert/8367
www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.39
www.openwall.com/lists/oss-security/2011/05/09/2
bugzilla.redhat.com/show_bug.cgi?id=703016