batman-adv: Remove hdr_size skb size check in batadv_interface_rx

The callers of batadv_interface_rx have to make sure that enough data can
be pulled from the skb when they read the batman-adv header. The only two
functions using it are either calling pskb_may_pull with hdr_size directly
(batadv_recv_bcast_packet) or indirectly via batadv_check_unicast_packet
(batadv_recv_unicast_packet).

Reported-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>

net/batman-adv/soft-interface.c

@@ -413,10 +413,6 @@ void batadv_interface_rx(struct net_device *soft_iface,
 	batadv_bcast_packet = (struct batadv_bcast_packet *)skb->data;
 	is_bcast = (batadv_bcast_packet->packet_type == BATADV_BCAST);
 
-	/* check if enough space is available for pulling, and pull */
-	if (!pskb_may_pull(skb, hdr_size))
-		goto dropped;
-
 	skb_pull_rcsum(skb, hdr_size);
 	skb_reset_mac_header(skb);