From: Linus Lüssing &lt;linus.luessing(a)web.de&gt; commit 7f112af40fecf5399b61e69ffc6b55a9d82789f7 upstream. So far the crc16 checksum for a batman-adv broadcast data packet, received on a batman-adv hard interface, was calculated over zero bytes of its content leading to many incoming broadcast data packets wrongly being dropped (60-80% packet loss). This patch fixes this issue by calculating the crc16 over the actual, complete broadcast payload. The issue is a regression introduced by ("batman-adv: add broadcast duplicate check"). Signed-off-by: Linus Lüssing &lt;linus.luessing(a)web.de&gt; Acked-by: Simon Wunderlich &lt;siwu(a)hrz.tu-chemnitz.de&gt; Signed-off-by: Marek Lindner &lt;lindner_marek(a)yahoo.de&gt; Signed-off-by: Antonio Quartulli &lt;ordex(a)autistici.org&gt; --- net/batman-adv/bridge_loop_avoidance.c | 16 +++++++--------- net/batman-adv/routing.c | 8 +++++++- 2 files changed, 14 insertions(+), 10 deletions(-) diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c index c5863f4..740bb6f 100644 --- a/net/batman-adv/bridge_loop_avoidance.c +++ b/net/batman-adv/bridge_loop_avoidance.c @@ -1172,8 +1172,8 @@ int bla_init(struct bat_priv *bat_priv) /** * @bat_priv: the bat priv with all the soft interface information - * @bcast_packet: originator mac address - * @hdr_size: maximum length of the frame + * @bcast_packet: encapsulated broadcast frame plus batman header + * @bcast_packet_len: length of encapsulated broadcast frame plus batman header * * check if it is on our broadcast list. Another gateway might * have sent the same packet because it is connected to the same backbone, @@ -1183,19 +1183,17 @@ int bla_init(struct bat_priv *bat_priv) * with a good chance that it is the same packet. If it is furthermore * sent by another host, drop it. We allow equal packets from * the same host however as this might be intended. - * - **/ - -int bla_check_bcast_duplist(struct bat_priv *bat_priv, - struct bcast_packet *bcast_packet, - int hdr_size) + */ +int batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv, + struct batadv_bcast_packet *bcast_packet, + int bcast_packet_len) { int i, length, curr; uint8_t *content; uint16_t crc; struct bcast_duplist_entry *entry; - length = hdr_size - sizeof(*bcast_packet); + length = bcast_packet_len - sizeof(*bcast_packet); content = (uint8_t *)bcast_packet; content += sizeof(*bcast_packet); diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c index 015471d..0c2cb6b 100644 --- a/net/batman-adv/routing.c +++ b/net/batman-adv/routing.c @@ -1081,8 +1081,14 @@ int recv_bcast_packet(struct sk_buff *skb, struct hard_iface *recv_if) spin_unlock_bh(&orig_node->bcast_seqno_lock); + /* keep skb linear for crc calculation */ + if (skb_linearize(skb) < 0) + goto out; + + bcast_packet = (struct batadv_bcast_packet *)skb->data; + /* check whether this has been sent by another originator before */ - if (bla_check_bcast_duplist(bat_priv, bcast_packet, hdr_size)) + if (batadv_bla_check_bcast_duplist(bat_priv, bcast_packet, skb->len)) goto out; /* rebroadcast packet */ -- 1.8.0