[PATCH 5.10 11/23] batman-adv: tp_meter: initialize last_recv_time during init

[Sven Eckelmann <sven@narfation.org>]

commit 811cb00fa8cdc3f0a7f6eefc000a6888367c8c8f upstream.

The last_recv_time is the most important indicator for a receiver session
to figure out whether a session timed out or not. But this information was
only initialized after the session was added to the tp_receiver_list and
after the timer was started.

In the worst case, the timer (function) could have tried to access this
information before the actual initialization was reached. Like rest of the
variables of the tp_meter receiver session, this field has to be filled out
before any other (parallel running) context has the chance to access it.

Cc: stable@kernel.org
Fixes: 33a3bb4a3345 ("batman-adv: throughput meter implementation")
[ Context ]
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 net/batman-adv/tp_meter.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/net/batman-adv/tp_meter.c b/net/batman-adv/tp_meter.c
index a015ff73812f5..ea5640242ddc2 100644
--- a/net/batman-adv/tp_meter.c
+++ b/net/batman-adv/tp_meter.c
@@ -1412,8 +1412,10 @@ batadv_tp_init_recv(struct batadv_priv *bat_priv,
 
 	tp_vars = batadv_tp_list_find_session(bat_priv, icmp->orig,
 					      icmp->session, BATADV_TP_RECEIVER);
-	if (tp_vars)
+	if (tp_vars) {
+		tp_vars->last_recv_time = jiffies;
 		goto out_unlock;
+	}
 
 	if (!atomic_add_unless(&bat_priv->tp_num, 1, BATADV_TP_MAX_NUM)) {
 		batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
@@ -1440,6 +1442,8 @@ batadv_tp_init_recv(struct batadv_priv *bat_priv,
 	kref_get(&tp_vars->refcount);
 	timer_setup(&tp_vars->timer, batadv_tp_receiver_shutdown, 0);
 
+	tp_vars->last_recv_time = jiffies;
+
 	kref_get(&tp_vars->refcount);
 	hlist_add_head_rcu(&tp_vars->list, &bat_priv->tp_list);
 
@@ -1488,9 +1492,9 @@ static void batadv_tp_recv_msg(struct batadv_priv *bat_priv,
 				   icmp->orig);
 			goto out;
 		}
-	}
 
-	tp_vars->last_recv_time = jiffies;
+		tp_vars->last_recv_time = jiffies;
+	}
 
 	/* if the packet is a duplicate, it may be the case that an ACK has been
 	 * lost. Resend the ACK
-- 
2.47.3