Patch "batman-adv: Drop immediate neigh_ifinfo free function" has been added to the 4.4-stable tree

Patch "batman-adv: Drop immediate neigh_ifinfo free function" has been added to the 4.4-stable tree

[gregkh]

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

    batman-adv: Drop immediate neigh_ifinfo free function

to the 4.4-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:
     batman-adv-drop-immediate-neigh_ifinfo-free-function.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Tue Jan 26 21:31:27 PST 2016
From: Sven Eckelmann <sven@narfation.org>
Date: Tue, 5 Jan 2016 12:06:24 +0100
Subject: batman-adv: Drop immediate neigh_ifinfo free function

From: Sven Eckelmann <sven@narfation.org>

[ Upstream commit ae3e1e36e3cb6c686a7a2725af20ca86aa46d62a ]

It is not allowed to free the memory of an object which is part of a list
which is protected by rcu-read-side-critical sections without making sure
that no other context is accessing the object anymore. This usually happens
by removing the references to this object and then waiting until the rcu
grace period is over and no one (allowedly) accesses it anymore.

But the _now functions ignore this completely. They free the object
directly even when a different context still tries to access it. This has
to be avoided and thus these functions must be removed and all functions
have to use batadv_neigh_ifinfo_free_ref.

Fixes: 89652331c00f ("batman-adv: split tq information in neigh_node struct")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/batman-adv/originator.c |   34 ++++++++++------------------------
 1 file changed, 10 insertions(+), 24 deletions(-)

--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -163,42 +163,28 @@ err:
 }
 
 /**
- * batadv_neigh_ifinfo_free_rcu - free the neigh_ifinfo object
- * @rcu: rcu pointer of the neigh_ifinfo object
- */
-static void batadv_neigh_ifinfo_free_rcu(struct rcu_head *rcu)
-{
-	struct batadv_neigh_ifinfo *neigh_ifinfo;
-
-	neigh_ifinfo = container_of(rcu, struct batadv_neigh_ifinfo, rcu);
-
-	if (neigh_ifinfo->if_outgoing != BATADV_IF_DEFAULT)
-		batadv_hardif_free_ref_now(neigh_ifinfo->if_outgoing);
-
-	kfree(neigh_ifinfo);
-}
-
-/**
- * batadv_neigh_ifinfo_free_now - decrement the refcounter and possibly free
- *  the neigh_ifinfo (without rcu callback)
+ * batadv_neigh_ifinfo_release - release neigh_ifinfo from lists and queue for
+ *  free after rcu grace period
  * @neigh_ifinfo: the neigh_ifinfo object to release
  */
 static void
-batadv_neigh_ifinfo_free_ref_now(struct batadv_neigh_ifinfo *neigh_ifinfo)
+batadv_neigh_ifinfo_release(struct batadv_neigh_ifinfo *neigh_ifinfo)
 {
-	if (atomic_dec_and_test(&neigh_ifinfo->refcount))
-		batadv_neigh_ifinfo_free_rcu(&neigh_ifinfo->rcu);
+	if (neigh_ifinfo->if_outgoing != BATADV_IF_DEFAULT)
+		batadv_hardif_free_ref(neigh_ifinfo->if_outgoing);
+
+	kfree_rcu(neigh_ifinfo, rcu);
 }
 
 /**
- * batadv_neigh_ifinfo_free_ref - decrement the refcounter and possibly free
+ * batadv_neigh_ifinfo_free_ref - decrement the refcounter and possibly release
  *  the neigh_ifinfo
  * @neigh_ifinfo: the neigh_ifinfo object to release
  */
 void batadv_neigh_ifinfo_free_ref(struct batadv_neigh_ifinfo *neigh_ifinfo)
 {
 	if (atomic_dec_and_test(&neigh_ifinfo->refcount))
-		call_rcu(&neigh_ifinfo->rcu, batadv_neigh_ifinfo_free_rcu);
+		batadv_neigh_ifinfo_release(neigh_ifinfo);
 }
 
 /**
@@ -217,7 +203,7 @@ static void batadv_neigh_node_free_rcu(s
 
 	hlist_for_each_entry_safe(neigh_ifinfo, node_tmp,
 				  &neigh_node->ifinfo_list, list) {
-		batadv_neigh_ifinfo_free_ref_now(neigh_ifinfo);
+		batadv_neigh_ifinfo_free_ref(neigh_ifinfo);
 	}
 
 	if (bao->bat_neigh_free)


Patches currently in stable-queue which might be from sven@narfation.org are

queue-4.4/batman-adv-drop-immediate-batadv_neigh_node-free-function.patch
queue-4.4/batman-adv-drop-immediate-neigh_ifinfo-free-function.patch
queue-4.4/batman-adv-drop-immediate-orig_node-free-function.patch
queue-4.4/batman-adv-drop-immediate-batadv_orig_ifinfo-free-function.patch
queue-4.4/batman-adv-avoid-recursive-call_rcu-for-batadv_nc_node.patch
queue-4.4/batman-adv-drop-immediate-batadv_hard_iface-free-function.patch
queue-4.4/batman-adv-avoid-recursive-call_rcu-for-batadv_bla_claim.patch