Patch "apparmor: fix refcount race when finding a child profile" has been added to the 4.7-stable tree

This is a note to let you know that I've just added the patch titled

apparmor: fix refcount race when finding a child profile

to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
apparmor-fix-refcount-race-when-finding-a-child-profile.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: John Johansen <[email protected]>
Date: Wed, 16 Dec 2015 18:09:10 -0800
Subject: apparmor: fix refcount race when finding a child profile

From: John Johansen <[email protected]>

commit de7c4cc947f9f56f61520ee7edaf380434a98c8d upstream.

When finding a child profile via an rcu critical section, the profile may be put and scheduled for deletion after the child is found but before its refcount is incremented.

Protect against this by repeating the lookup if the profiles refcount is 0 and is one its way to deletion.

---
 security/apparmor/policy.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

@@ -766,7 +766,9 @@ struct aa_profile *aa_find_child(struct
 	struct aa_profile *profile;
 
 	rcu_read_lock();
-	profile = aa_get_profile(__find_child(&parent->base.profiles, name));
+	do {
+		profile = __find_child(&parent->base.profiles, name);
+	} while (profile && !aa_get_profile_not0(profile));
 	rcu_read_unlock();
 
 	/* refcount released by caller */

Patches currently in stable-queue which might be from [email protected] are

queue-4.7/apparmor-fix-refcount-race-when-finding-a-child-profile.patch