Patch "batman-adv: protect tt_local_entry from concurrent delete events" has been added to the 4.1-stable tree

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

batman-adv: protect tt_local_entry from concurrent delete events

to the 4.1-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-protect-tt_local_entry-from-concurrent-delete-events.patch
and it can be found in the queue-4.1 subdirectory.

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

From: Marek Lindner <[email protected]>
Date: Wed, 17 Jun 2015 20:01:36 +0800
Subject: batman-adv: protect tt_local_entry from concurrent delete events

From: Marek Lindner <[email protected]>

commit ef72706a0543d0c3a5ab29bd6378fdfb368118d9 upstream.

The tt_local_entry deletion performed in batadv_tt_local_remove() was neither protecting against simultaneous deletes nor checking whether the element was still part of the list before calling hlist_del_rcu().

Replacing the hlist_del_rcu() call with batadv_hash_remove() provides adequate protection via hash spinlocks as well as an is-element-still-in-hash check to avoid 'blind' hash removal.

---
 net/batman-adv/translation-table.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

@@ -1018,6 +1018,7 @@ uint16_t batadv_tt_local_remove(struct b
 	struct batadv_tt_local_entry *tt_local_entry;
 	uint16_t flags, curr_flags = BATADV_NO_FLAGS;
 	struct batadv_softif_vlan *vlan;
+	void *tt_entry_exists;
 
 	tt_local_entry = batadv_tt_local_hash_find(bat_priv, addr, vid);
 	if (!tt_local_entry)

@@ -1045,7 +1046,15 @@ uint16_t batadv_tt_local_remove(struct b
 	 * immediately purge it
 	 */
 	batadv_tt_local_event(bat_priv, tt_local_entry, BATADV_TT_CLIENT_DEL);
-	hlist_del_rcu(&tt_local_entry->common.hash_entry);
+
+	tt_entry_exists = batadv_hash_remove(bat_priv->tt.local_hash,
+					     batadv_compare_tt,
+					     batadv_choose_tt,
+					     &tt_local_entry->common);
+	if (!tt_entry_exists)
+		goto out;
+
+	/* extra call to free the local tt entry */
 	batadv_tt_local_entry_free_ref(tt_local_entry);
 
 	/* decrease the reference held for this vlan */

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

queue-4.1/batman-adv-fix-kernel-crash-due-to-missing-null-checks.patch queue-4.1/batman-adv-make-dat-capability-changes-atomic.patch queue-4.1/batman-adv-protect-tt_local_entry-from-concurrent-delete-events.patch