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batman-adv: protect tt_local_entry from concurrent delete events

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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.

Fixes: 068ee6e204 ("batman-adv: roaming handling mechanism redesign")
Reported-by: alfonsname@web.de
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
This commit is contained in:
Marek Lindner 2015-06-17 20:01:36 +08:00 committed by Antonio Quartulli
parent 354136bcc3
commit ef72706a05
1 changed files with 10 additions and 1 deletions
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11
net/batman-adv/translation-table.c
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@ -1037,6 +1037,7 @@ uint16_t batadv_tt_local_remove(struct batadv_priv *bat_priv,
struct batadv_tt_local_entry *tt_local_entry; struct batadv_tt_local_entry *tt_local_entry;
uint16_t flags, curr_flags = BATADV_NO_FLAGS; uint16_t flags, curr_flags = BATADV_NO_FLAGS;
struct batadv_softif_vlan *vlan; struct batadv_softif_vlan *vlan;
void *tt_entry_exists;
tt_local_entry = batadv_tt_local_hash_find(bat_priv, addr, vid); tt_local_entry = batadv_tt_local_hash_find(bat_priv, addr, vid);
if (!tt_local_entry) if (!tt_local_entry)
@ -1064,7 +1065,15 @@ uint16_t batadv_tt_local_remove(struct batadv_priv *bat_priv,
* immediately purge it * immediately purge it
*/ */
batadv_tt_local_event(bat_priv, tt_local_entry, BATADV_TT_CLIENT_DEL); 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); batadv_tt_local_entry_free_ref(tt_local_entry);
/* decrease the reference held for this vlan */ /* decrease the reference held for this vlan */