[B.A.T.M.A.N.] [PATCH-maint 1/2] batman-adv: Only put gw_node list reference when removed

[B.A.T.M.A.N.] [PATCH-maint 1/2] batman-adv: Only put gw_node list reference when removed

[Sven Eckelmann]

The batadv_gw_node reference counter in batadv_gw_node_update can only be
reduced when the list entry was actually removed. Otherwise the reference
counter may reach zero when batadv_gw_node_update is called from two
different contexts for the same gw_node but only one context is actually
removing the entry from the list.

The release function for this gw_node is not called inside the list_lock
spinlock protected region because the function batadv_gw_node_update still
holds a gw_node reference for the object pointer on the stack. Thus the
actual release function (when required) will be called only at the end of
the function.

Fixes: 0511575c4d03 ("batman-adv: remove obsolete deleted attribute for gateway node")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 net/batman-adv/gateway_client.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c
index 8350775..c9b8b48 100644
--- a/net/batman-adv/gateway_client.c
+++ b/net/batman-adv/gateway_client.c
@@ -527,11 +527,12 @@ void batadv_gw_node_update(struct batadv_priv *bat_priv,
 		 * gets dereferenced.
 		 */
 		spin_lock_bh(&bat_priv->gw.list_lock);
-		hlist_del_init_rcu(&gw_node->list);
+		if (!hlist_unhashed(&gw_node->list)) {
+			hlist_del_init_rcu(&gw_node->list);
+			batadv_gw_node_free_ref(gw_node);
+		}
 		spin_unlock_bh(&bat_priv->gw.list_lock);
 
-		batadv_gw_node_free_ref(gw_node);
-
 		curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 		if (gw_node == curr_gw)
 			batadv_gw_reselect(bat_priv);
-- 
2.7.0

[B.A.T.M.A.N.] [PATCH-maint 2/2] batman-adv: Only put orig_node_vlan list reference when removed

[Sven Eckelmann]

The batadv_orig_node_vlan reference counter in batadv_tt_global_size_mod
can only be reduced when the list entry was actually removed. Otherwise the
reference counter may reach zero when batadv_tt_global_size_mod is called
from two different contexts for the same orig_node_vlan but only one
context is actually removing the entry from the list.

The release function for this orig_node_vlan is not called inside the
vlan_list_lock spinlock protected region because the function
batadv_tt_global_size_mod still holds a orig_node_vlan reference for the
object pointer on the stack. Thus the actual release function (when
required) will be called only at the end of the function.

Fixes: 21a57f6e7a3b ("batman-adv: make the TT CRC logic VLAN specific")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 net/batman-adv/translation-table.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index 9fcf6bf..7301a92 100644
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -311,9 +311,11 @@ static void batadv_tt_global_size_mod(struct batadv_orig_node *orig_node,
 
 	if (atomic_add_return(v, &vlan->tt.num_entries) == 0) {
 		spin_lock_bh(&orig_node->vlan_list_lock);
-		hlist_del_init_rcu(&vlan->list);
+		if (!hlist_unhashed(&vlan->list)) {
+			hlist_del_init_rcu(&vlan->list);
+			batadv_orig_node_vlan_free_ref(vlan);
+		}
 		spin_unlock_bh(&orig_node->vlan_list_lock);
-		batadv_orig_node_vlan_free_ref(vlan);
 	}
 
 	batadv_orig_node_vlan_free_ref(vlan);
-- 
2.7.0

Re: [B.A.T.M.A.N.] [PATCH-maint 2/2] batman-adv: Only put orig_node_vlan list reference when removed

[Marek Lindner]

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On Sunday, January 31, 2016 13:28:00 Sven Eckelmann wrote:
> The batadv_orig_node_vlan reference counter in batadv_tt_global_size_mod
> can only be reduced when the list entry was actually removed. Otherwise the
> reference counter may reach zero when batadv_tt_global_size_mod is called
> from two different contexts for the same orig_node_vlan but only one
> context is actually removing the entry from the list.
> 
> The release function for this orig_node_vlan is not called inside the
> vlan_list_lock spinlock protected region because the function
> batadv_tt_global_size_mod still holds a orig_node_vlan reference for the
> object pointer on the stack. Thus the actual release function (when
> required) will be called only at the end of the function.
> 
> Fixes: 21a57f6e7a3b ("batman-adv: make the TT CRC logic VLAN specific")
> Signed-off-by: Sven Eckelmann <sven@narfation.org>
> ---
>  net/batman-adv/translation-table.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)

Applied in revision ead9389.

Thanks,
Marek

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Re: [B.A.T.M.A.N.] [PATCH-maint 1/2] batman-adv: Only put gw_node list reference when removed

[Marek Lindner]

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On Sunday, January 31, 2016 13:27:59 Sven Eckelmann wrote:
> The batadv_gw_node reference counter in batadv_gw_node_update can only be
> reduced when the list entry was actually removed. Otherwise the reference
> counter may reach zero when batadv_gw_node_update is called from two
> different contexts for the same gw_node but only one context is actually
> removing the entry from the list.
> 
> The release function for this gw_node is not called inside the list_lock
> spinlock protected region because the function batadv_gw_node_update still
> holds a gw_node reference for the object pointer on the stack. Thus the
> actual release function (when required) will be called only at the end of
> the function.
> 
> Fixes: 0511575c4d03 ("batman-adv: remove obsolete deleted attribute for
> gateway node") Signed-off-by: Sven Eckelmann <sven@narfation.org>
> ---
>  net/batman-adv/gateway_client.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)

Applied in revision c215e4e.

Thanks,
Marek

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