[PATCH net 5/8] batman-adv: tp_meter: fix tp_num leak on kmalloc failure

From: Sven Eckelmann <[email protected]>

When batadv_tp_start() or batadv_tp_init_recv() fail to allocate a new
tp_vars object, the previously incremented bat_priv->tp_num counter is
never decremented. This causes tp_num to drift upward on each allocation
failure. Since only BATADV_TP_MAX_NUM sessions can be started and the count
is never reduced for these failed allocations, it causes to an exhaustion
of throughput meter sessions. In worst case, no new throughput meter
session can be started until the mesh interface is removed.

The error handling must decrement tp_num releasing the lock and aborting
the creation of an throughput meter session

Cc: [email protected]
Fixes: 33a3bb4a3345 ("batman-adv: throughput meter implementation")
Signed-off-by: Sven Eckelmann <[email protected]>
Signed-off-by: Simon Wunderlich <[email protected]>
---
 net/batman-adv/tp_meter.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/batman-adv/tp_meter.c b/net/batman-adv/tp_meter.c
index 58ca59a2799ed..066c76113fc43 100644
--- a/net/batman-adv/tp_meter.c
+++ b/net/batman-adv/tp_meter.c
@@ -994,6 +994,7 @@ void batadv_tp_start(struct batadv_priv *bat_priv, const u8 *dst,
 
 	tp_vars = kmalloc_obj(*tp_vars, GFP_ATOMIC);
 	if (!tp_vars) {
+		atomic_dec(&bat_priv->tp_num);
 		spin_unlock_bh(&bat_priv->tp_list_lock);
 		batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 			   "Meter: %s cannot allocate list elements\n",
@@ -1366,8 +1367,10 @@ batadv_tp_init_recv(struct batadv_priv *bat_priv,
 	}
 
 	tp_vars = kmalloc_obj(*tp_vars, GFP_ATOMIC);
-	if (!tp_vars)
+	if (!tp_vars) {
+		atomic_dec(&bat_priv->tp_num);
 		goto out_unlock;
+	}
 
 	ether_addr_copy(tp_vars->other_end, icmp->orig);
 	tp_vars->role = BATADV_TP_RECEIVER;
-- 
2.47.3