batman-adv: Don't schedule OGM for disabled interface

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: b01d4991e36e ("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>

diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
index f0209505e41ae1a4bba6989dc571906dc46f432d..a7c8dd7ae51314f3fd729484300b0796238a87c8 100644 (file)
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -789,6 +789,10 @@ static void batadv_iv_ogm_schedule_buff(struct batadv_hard_iface *hard_iface)
 
        lockdep_assert_held(&hard_iface->bat_iv.ogm_buff_mutex);
 
+       /* 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