]> git.karo-electronics.de Git - karo-tx-linux.git/commit
device_cgroup: fix RCU usage
authorTejun Heo <tj@kernel.org>
Tue, 6 Nov 2012 17:17:37 +0000 (09:17 -0800)
committerBen Hutchings <ben@decadent.org.uk>
Thu, 6 Dec 2012 11:20:03 +0000 (11:20 +0000)
commitc5ee58688baa98bc3a4f6095a1acf6fd7fd9e967
tree246b22df83e054ef912999e82f9dae6f58acd33c
parent3e1fab33b18e2b10581e2e163ee74ec3d040a09a
device_cgroup: fix RCU usage

commit 201e72acb2d3821e2de9ce6091e98859c316b29a upstream.

dev_cgroup->exceptions is protected with devcgroup_mutex for writes
and RCU for reads; however, RCU usage isn't correct.

* dev_exception_clean() doesn't use RCU variant of list_del() and
  kfree().  The function can race with may_access() and may_access()
  may end up dereferencing already freed memory.  Use list_del_rcu()
  and kfree_rcu() instead.

* may_access() may be called only with RCU read locked but doesn't use
  RCU safe traversal over ->exceptions.  Use list_for_each_entry_rcu().

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Cc: Aristeu Rozanski <aris@redhat.com>
Cc: Li Zefan <lizefan@huawei.com>
[bwh: Backported to 3.2:
 - Adjust context
 - Exception list is called whitelist]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
security/device_cgroup.c