When we receive an OGM from from a node for the first time, the last_real_seqno
field of the orig_node structure has not been initialised yet. The value of this
field is used to compute the current ogm-seqno window and therefore the
protection mechanism will probably drop the packet due to an out-of-window 
error.
To avoid this situation this patch adds a check to skip the window protection
mechanism if no neighbour nodes have already been added. When the first
neighbour node is added, the last_real_seqno field is initialised too.

Reported-by: Marek Lindner <lindner_ma...@yahoo.de>
Signed-off-by: Antonio Quartulli <or...@autistici.org>
---
 net/batman-adv/bat_iv_ogm.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
index 1014210..8b2db2e 100644
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -861,7 +861,8 @@ static int bat_iv_ogm_update_seqnos(const struct ethhdr 
*ethhdr,
        seq_diff = batman_ogm_packet->seqno - orig_node->last_real_seqno;
 
        /* signalize caller that the packet is to be dropped. */
-       if (window_protected(bat_priv, seq_diff,
+       if (!hlist_empty(&orig_node->neigh_list) &&
+           window_protected(bat_priv, seq_diff,
                             &orig_node->batman_seqno_reset))
                goto out;
 
-- 
1.7.9.4

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