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Subject[ 33/66] batman-adv: Fix broadcast packet CRC calculation
Date
3.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Linus Lüssing <linus.luessing@web.de>

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 <linus.luessing@web.de>
Acked-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/batman-adv/bridge_loop_avoidance.c | 8 ++++----
net/batman-adv/routing.c | 8 +++++++-
2 files changed, 11 insertions(+), 5 deletions(-)

--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -1205,8 +1205,8 @@ int batadv_bla_init(struct batadv_priv *
/**
* batadv_bla_check_bcast_duplist
* @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,
@@ -1219,14 +1219,14 @@ int batadv_bla_init(struct batadv_priv *
*/
int batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv,
struct batadv_bcast_packet *bcast_packet,
- int hdr_size)
+ int bcast_packet_len)
{
int i, length, curr;
uint8_t *content;
uint16_t crc;
struct batadv_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);

--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -1136,8 +1136,14 @@ int batadv_recv_bcast_packet(struct sk_b

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 (batadv_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 */

--
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