tree c450d64f0d12d756cfbb38df0ccfdb710e07d7cb
parent e6413c8a91fe9736c2401fc223350bb8d82c7980
author John Johansen <john.johansen@canonical.com> 1772410251 -0800
committer Cloud Image Release <cloud-image-release@prod.google.com> 1773439287 -0700

apparmor: fix race between freeing data and fs accessing it

commit 8e135b8aee5a06c52a4347a5a6d51223c6f36ba3 upstream.

AppArmor was putting the reference to i_private data on its end after
removing the original entry from the file system. However the inode
can aand does live beyond that point and it is possible that some of
the fs call back functions will be invoked after the reference has
been put, which results in a race between freeing the data and
accessing it through the fs.

While the rawdata/loaddata is the most likely candidate to fail the
race, as it has the fewest references. If properly crafted it might be
possible to trigger a race for the other types stored in i_private.

Fix this by moving the put of i_private referenced data to the correct
place which is during inode eviction.

BUG=None
TEST=presubmit
RELEASE_NOTE=Fixed the "CrackArmor" vulnerability in the Linux kernel.

cos-patch: security-high
Fixes: c961ee5f21b20 ("apparmor: convert from securityfs to apparmorfs for policy ns files")
Reported-by: Qualys Security Advisory <qsa@qualys.com>
Reviewed-by: Georgia Garcia <georgia.garcia@canonical.com>
Reviewed-by: Maxime Bélair <maxime.belair@canonical.com>
Reviewed-by: Cengiz Can <cengiz.can@canonical.com>
Change-Id: I609b901d5aee9aff6b28dc6b52eb1ca8e879eecd
Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit eecce026399917f6efa532c56bc7a3e9dd6ee68b)
Signed-off-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/137882
Main-Branch-Verified: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: He Gao <hegao@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/137951