[PATCH AUTOSEL 4.9 01/15] batman-adv: Don't schedule OGM for disabled interface

[Sasha Levin <sashal@kernel.org>]

From: Sven Eckelmann <sven@narfation.org>

[ Upstream commit 8e8ce08198de193e3d21d42e96945216e3d9ac7f ]

A transmission scheduling for an interface which is currently dropped by
batadv_iv_ogm_iface_disable could still be in progress. The B.A.T.M.A.N. V
is simply cancelling the workqueue item in an synchronous way but this is
not possible with B.A.T.M.A.N. IV because the OGM submissions are
intertwined.

Instead it has to stop submitting the OGM when it detect that the buffer
pointer is set to NULL.

Reported-by: syzbot+a98f2016f40b9cd3818a@syzkaller.appspotmail.com
Reported-by: syzbot+ac36b6a33c28a491e929@syzkaller.appspotmail.com
Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Cc: Hillf Danton <hdanton@sina.com>
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, 4 insertions(+)

diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
index 780700fcbe63e..b08e3b331c503 100644
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -934,6 +934,10 @@ static void batadv_iv_ogm_schedule(struct batadv_hard_iface *hard_iface)
 	    (hard_iface->if_status == BATADV_IF_TO_BE_REMOVED))
 		return;
 
+	/* interface already disabled by batadv_iv_ogm_iface_disable */
+	if (!*ogm_buff)
+		return;
+
 	/* the interface gets activated here to avoid race conditions between
 	 * the moment of activating the interface in
 	 * hardif_activate_interface() where the originator mac is set and
-- 
2.20.1