CVE-2011-1771 kernel: cifs oops when creating file with O_DIRECT set

[Eugene Teo <eugene () redhat com>]

CIFS does not do O_DIRECT, so when you open a file with it, you will 
trigger a NULL pointer dereference. This is a regression introduced with 
the patchset to clean up filehandle management in CIFS. The fix checks 
for a NULL filp->private_data before trying to dereference it.

http://marc.info/?l=linux-cifs&m=130204730006155&w=2
https://bugzilla.redhat.com/CVE-2011-1771

Introduced by cdff08e7 (v2.6.37-rc1)

Upstream commit
http://git.kernel.org/linus/77970693

Thanks, Eugene