[PATCH 3.16 099/305] batman-adv: fix skb deref after free

Ben Hutchings
2016-08-14T18:13:17Z

From: Florian Westphal <fw@strlen.de>

commit 63d443efe8be2c1d02b30d7e4edeb9aa085352b3 upstream.

batadv_send_skb_to_orig() calls dev_queue_xmit() so we can't use skb->len.

Fixes: 953324776d6d ("batman-adv: network coding - buffer unicast packets before forward")
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/batman-adv/routing.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -568,6 +568,7 @@ static int batadv_route_unicast_packet(s
struct batadv_unicast_packet *unicast_packet;
struct ethhdr *ethhdr = eth_hdr(skb);
int res, hdr_len, ret = NET_RX_DROP;
+ unsigned int len;

unicast_packet = (struct batadv_unicast_packet *)skb->data;

@@ -608,6 +609,7 @@ static int batadv_route_unicast_packet(s
if (hdr_len > 0)
batadv_skb_set_priority(skb, hdr_len);

+ len = skb->len;
res = batadv_send_skb_to_orig(skb, orig_node, recv_if);

/* translate transmit result into receive result */
@@ -615,7 +617,7 @@ static int batadv_route_unicast_packet(s
/* skb was transmitted and consumed */
batadv_inc_counter(bat_priv, BATADV_CNT_FORWARD);
batadv_add_counter(bat_priv, BATADV_CNT_FORWARD_BYTES,
- skb->len + ETH_HLEN);
+ len + ETH_HLEN);

ret = NET_RX_SUCCESS;
} else if (res == NET_XMIT_POLICED) {