[PATCH 4.9 18/71] batman-adv: Avoid WARN_ON timing related checks

Sasha Levin
2021-06-28T15:19:34Z

From: Sven Eckelmann <sven@narfation.org>

[ Upstream commit 9f460ae31c4435fd022c443a6029352217a16ac1 ]

The soft/batadv interface for a queued OGM can be changed during the time
the OGM was queued for transmission and when the OGM is actually
transmitted by the worker.

But WARN_ON must be used to denote kernel bugs and not to print simple
warnings. A warning can simply be printed using pr_warn.

Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Reported-by: syzbot+c0b807de416427ff3dd1@syzkaller.appspotmail.com
Fixes: ef0a937f7a14 ("batman-adv: consider outgoing interface in OGM sending")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/batman-adv/bat_iv_ogm.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
index 2b663622bdb4..f85e6a9ee5ea 100644
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -585,8 +585,10 @@ static void batadv_iv_ogm_emit(struct batadv_forw_packet *forw_packet)
if (WARN_ON(!forw_packet->if_outgoing))
return;

- if (WARN_ON(forw_packet->if_outgoing->soft_iface != soft_iface))
+ if (forw_packet->if_outgoing->soft_iface != soft_iface) {
+ pr_warn("%s: soft interface switch for queued OGM\n", __func__);
return;
+ }

if (forw_packet->if_incoming->if_status != BATADV_IF_ACTIVE)
return;
--
2.30.2