[B.A.T.M.A.N.] [PATCH maint] batman-adv: Avoid probe ELP information leak

[Sven Eckelmann <sven@narfation.org>]

The probe ELPs for WiFi interfaces are expanded to contain at least
BATADV_ELP_MIN_PROBE_SIZE bytes. This is usually a lot more than the
number of bytes which the template ELP packet requires.

These extra padding bytes were not initialized and thus could contain data
which were previously stored at the same location. It is therefore required
to set it to some predefined or random values to avoid leaking private
information from the system transmitting these kind of packets.

Fixes: bedcadfaa92b ("batman-adv: ELP - send unicast ELP packets for throughput sampling")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 net/batman-adv/bat_v_elp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/batman-adv/bat_v_elp.c b/net/batman-adv/bat_v_elp.c
index 71c20c1d..e103c759 100644
--- a/net/batman-adv/bat_v_elp.c
+++ b/net/batman-adv/bat_v_elp.c
@@ -241,7 +241,7 @@ batadv_v_elp_wifi_neigh_probe(struct batadv_hardif_neigh_node *neigh)
 		 * the packet to be exactly of that size to make the link
 		 * throughput estimation effective.
 		 */
-		skb_put(skb, probe_len - hard_iface->bat_v.elp_skb->len);
+		skb_put_zero(skb, probe_len - hard_iface->bat_v.elp_skb->len);
 
 		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 			   "Sending unicast (probe) ELP packet on interface %s to %pM\n",
-- 
2.18.0