diff mbox

[maint,2/2] batman-adv: Only put orig_node_vlan list reference when removed

Message ID 1454243280-15126-2-git-send-email-sven@narfation.org (mailing list archive)
State Accepted, archived
Commit ead9389a3a0af4de210c977a0b11d57180d7c941
Headers

Commit Message

Sven Eckelmann Jan. 31, 2016, 12:28 p.m. UTC 
  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(-)

Comments

Marek Lindner Feb. 10, 2016, 10:45 a.m. UTC | #1 
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
diff mbox

Patch

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);