CVE-2012-4508 -- kernel: ext4: AIO vs fallocate stale data exposure

[Petr Matousek <pmatouse () redhat com>]

A race condition flaw has been found in the way asynchronous I/O and
fallocate interacted which can lead to exposure of stale data -- that
is, an extent which should have had the "uninitialized" bit set
indicating that its blocks have not yet been written and thus contain
data from a deleted file. An unprivileged local user could use this flaw
to cause an information leak.

Acknowledgements:

Red Hat would like to thank Theodore Tso for reporting this issue.
Upstream acknowledges Dmitry Monakhov as the original reporter.

Upstream fix:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=dee1f973ca341c266229faa5a1a5bb268bed3531

Please see https://bugzilla.redhat.com/show_bug.cgi?id=869904#c1 for
further information regarding the patch.

References:
https://bugzilla.redhat.com/show_bug.cgi?id=869904

Thanks,
-- 
Petr Matousek / Red Hat Security Response Team