batman-adv/patches/0010-batman-adv-protect-tt_local_entry-from-concurrent-de.patch

   1 From af912d77181f252e6fdd324592d006e30bc82909 Mon Sep 17 00:00:00 2001
   2 From: Marek Lindner <mareklindner@neomailbox.ch>
   3 Date: Wed, 17 Jun 2015 20:01:36 +0800
   4 Subject: [PATCH 10/13] batman-adv: protect tt_local_entry from concurrent
   5  delete events
   6
   7 The tt_local_entry deletion performed in batadv_tt_local_remove() was neither
   8 protecting against simultaneous deletes nor checking whether the element was
   9 still part of the list before calling hlist_del_rcu().
  10
  11 Replacing the hlist_del_rcu() call with batadv_hash_remove() provides adequate
  12 protection via hash spinlocks as well as an is-element-still-in-hash check to
  13 avoid 'blind' hash removal.
  14
  15 Fixes: 2443ba3 ("batman-adv: roaming handling mechanism redesign")
  16
  17 Reported-by: alfonsname@web.de
  18 Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
  19 Acked-by: Antonio Quartulli <antonio@meshcoding.com>
  20 ---
  21  translation-table.c | 11 ++++++++++-
  22  1 file changed, 10 insertions(+), 1 deletion(-)
  23
  24 diff --git a/translation-table.c b/translation-table.c
  25 index 807a4e6..dfe8896 100644
  26 --- a/translation-table.c
  27 +++ b/translation-table.c
  28 @@ -1019,6 +1019,7 @@ uint16_t batadv_tt_local_remove(struct batadv_priv *bat_priv,
  29         struct batadv_tt_local_entry *tt_local_entry;
  30         uint16_t flags, curr_flags = BATADV_NO_FLAGS;
  31         struct batadv_softif_vlan *vlan;
  32 +       void *tt_entry_exists;
  33
  34         tt_local_entry = batadv_tt_local_hash_find(bat_priv, addr, vid);
  35         if (!tt_local_entry)
  36 @@ -1046,7 +1047,15 @@ uint16_t batadv_tt_local_remove(struct batadv_priv *bat_priv,
  37          * immediately purge it
  38          */
  39         batadv_tt_local_event(bat_priv, tt_local_entry, BATADV_TT_CLIENT_DEL);
  40 -       hlist_del_rcu(&tt_local_entry->common.hash_entry);
  41 +
  42 +       tt_entry_exists = batadv_hash_remove(bat_priv->tt.local_hash,
  43 +                                            batadv_compare_tt,
  44 +                                            batadv_choose_tt,
  45 +                                            &tt_local_entry->common);
  46 +       if (!tt_entry_exists)
  47 +               goto out;
  48 +
  49 +       /* extra call to free the local tt entry */
  50         batadv_tt_local_entry_free_ref(tt_local_entry);
  51
  52         /* decrease the reference held for this vlan */
  53 --
  54 2.1.4
  55