batman-adv: check for tt_reponse packet real length

Before accessing the TT_RESPONSE packet payload, the node has to ensure that the
packet is long enough as it would expect to be.

Reported-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Sven Eckelmann <sven@narfation.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index e0e7b7b79ca9..ef24a7205f65 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -578,6 +578,7 @@ int recv_tt_query(struct sk_buff *skb, struct hard_iface *recv_if)
 {
         struct bat_priv *bat_priv = netdev_priv(recv_if->soft_iface);
         struct tt_query_packet *tt_query;
+        uint16_t tt_len;
         struct ethhdr *ethhdr;
 
         /* drop packet if it has not necessary minimum size */
@@ -622,6 +623,14 @@ int recv_tt_query(struct sk_buff *skb, struct hard_iface *recv_if)
                         if (skb_linearize(skb) < 0)
                                 goto out;
 
+                        tt_len = tt_query->tt_data * sizeof(struct tt_change);
+
+                        /* Ensure we have all the claimed data */
+                        if (unlikely(skb_headlen(skb) <
+                                        sizeof(struct tt_query_packet) +
+                                        tt_len))
+                                goto out;
+
                         handle_tt_response(bat_priv, tt_query);
                 } else {
                         bat_dbg(DBG_TT, bat_priv,