[PATCH net 12/14] batman-adv: tp_meter: avoid use of uninit sender vars

[Simon Wunderlich <sw@simonwunderlich.de>]

From: Sven Eckelmann <sven@narfation.org>

batadv_tp_recv_ack() and batadv_tp_stop() are only valid for tp_vars in the
BATADV_TP_SENDER role. When called with a BATADV_TP_RECEIVER role, it
proceeds to read sender-only members that were never initialized, leading
to undefined behavior.

This can be triggered when a node that is currently acting as a receiver in
an ongoing tp_meter session receives a malicious ACK packet.

Guard against this by checking tp_vars->role immediately after the
lookup and bailing out if it is not BATADV_TP_SENDER, before any of
those members are accessed.

Cc: stable@kernel.org
Fixes: 33a3bb4a3345 ("batman-adv: throughput meter implementation")
Reported-by: Yuan Tan <yuantan098@gmail.com>
Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Reviewed-by: Yuan Tan <yuantan098@gmail.com>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 net/batman-adv/tp_meter.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/net/batman-adv/tp_meter.c b/net/batman-adv/tp_meter.c
index ca6c3f6374bc5..a3593d104caa5 100644
--- a/net/batman-adv/tp_meter.c
+++ b/net/batman-adv/tp_meter.c
@@ -664,6 +664,9 @@ static void batadv_tp_recv_ack(struct batadv_priv *bat_priv,
 	if (unlikely(!tp_vars))
 		return;
 
+	if (unlikely(tp_vars->role != BATADV_TP_SENDER))
+		goto out;
+
 	if (unlikely(atomic_read(&tp_vars->sending) == 0))
 		goto out;
 
@@ -1101,12 +1104,16 @@ void batadv_tp_stop(struct batadv_priv *bat_priv, const u8 *dst,
 	if (!tp_vars) {
 		batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 			   "Meter: trying to interrupt an already over connection\n");
-		goto out;
+		goto out_put_orig_node;
 	}
 
+	if (unlikely(tp_vars->role != BATADV_TP_SENDER))
+		goto out_put_tp_vars;
+
 	batadv_tp_sender_shutdown(tp_vars, return_value);
+out_put_tp_vars:
 	batadv_tp_vars_put(tp_vars);
-out:
+out_put_orig_node:
 	batadv_orig_node_put(orig_node);
 }
 
-- 
2.47.3