batman-adv: verify tt len does not exceed packet len

batadv_iv_ogm_process() accesses the packet using the tt_num_changes
attribute regardless of the real packet len (assuming the length check
was done before). Therefore a length check is needed to avoid reading
random memory.

Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>

diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
index a0b253ecadaf6805106e74c943ed726a81f172bb..a5bb0a769eb927efff0408fa7dd6afbffcdf2ec0 100644 (file)
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -1288,7 +1288,8 @@ static int batadv_iv_ogm_receive(struct sk_buff *skb,
        batadv_ogm_packet = (struct batadv_ogm_packet *)packet_buff;
 
        /* unpack the aggregated packets and process them one by one */
-       do {
+       while (batadv_iv_ogm_aggr_packet(buff_pos, packet_len,
+                                        batadv_ogm_packet->tt_num_changes)) {
                tt_buff = packet_buff + buff_pos + BATADV_OGM_HLEN;
 
                batadv_iv_ogm_process(ethhdr, batadv_ogm_packet, tt_buff,
@@ -1299,8 +1300,7 @@ static int batadv_iv_ogm_receive(struct sk_buff *skb,
 
                packet_pos = packet_buff + buff_pos;
                batadv_ogm_packet = (struct batadv_ogm_packet *)packet_pos;
-       } while (batadv_iv_ogm_aggr_packet(buff_pos, packet_len,
-                                          batadv_ogm_packet->tt_num_changes));
+       }
 
        kfree_skb(skb);
        return NET_RX_SUCCESS;