[B.A.T.M.A.N.] [PATCH] batman-adv: protect tt_local_entry from concurrent delete events

[B.A.T.M.A.N.] [PATCH] batman-adv: protect tt_local_entry from concurrent delete events

[Marek Lindner]

The tt_local_entry deletion performed 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() with batadv_hash_remove() provides adequate
protection via hash spinlocks as well as a is-element-still-in-hash check.

Reported-by: alfonsname@web.de
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
---
 translation-table.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/translation-table.c b/translation-table.c
index e95a424..4afeeb5 100644
--- a/translation-table.c
+++ b/translation-table.c
@@ -1042,7 +1042,8 @@ uint16_t batadv_tt_local_remove(struct batadv_priv *bat_priv,
 	 * 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);
+	batadv_hash_remove(bat_priv->tt.local_hash, batadv_compare_tt,
+			   batadv_choose_tt, &tt_local_entry->common);
 	batadv_tt_local_entry_free_ref(tt_local_entry);
 
 	/* decrease the reference held for this vlan */
-- 
2.1.4

Re: [B.A.T.M.A.N.] [PATCH] batman-adv: protect tt_local_entry from concurrent delete events

[Antonio Quartulli]

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On 17/06/15 14:09, Marek Lindner wrote:
> The tt_local_entry deletion performed 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() with batadv_hash_remove() provides adequate
> protection via hash spinlocks as well as a is-element-still-in-hash check.
> 
> Reported-by: alfonsname@web.de
> Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>

Acked-by: Antonio Quartulli <antonio@meshcoding.com>

Thanks!

-- 
Antonio Quartulli


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Re: [B.A.T.M.A.N.] [PATCH] batman-adv: protect tt_local_entry from concurrent delete events

[Antonio Quartulli]

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On 17/06/15 14:36, Antonio Quartulli wrote:
> On 17/06/15 14:09, Marek Lindner wrote:
>> The tt_local_entry deletion performed 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() with batadv_hash_remove() provides adequate
>> protection via hash spinlocks as well as a is-element-still-in-hash check.
>>
>> Reported-by: alfonsname@web.de
>> Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
> 
> Acked-by: Antonio Quartulli <antonio@meshcoding.com>
> 

I was just going through your other TT patch and I realized that if the
element can't be find in the list (because it was already removed) we
should skip the batadv_softif_vlan_free_ref() below because the
reference has already been decreased by whom already removed the TT entry.


Cheers,

-- 
Antonio Quartulli


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