From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Fri, 16 Mar 2018 10:29:10 +0000 (+0100)
Subject: batman-adv: fix header size check in batadv_dbg_arp()
X-Git-Tag: v4.14.45~236
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=6b4a3d4e63f1a1a9d333224c082b57bbadcfab17;p=platform%2Fkernel%2Flinux-rpi.git

batman-adv: fix header size check in batadv_dbg_arp()

[ Upstream commit 6f27d2c2a8c236d296201c19abb8533ec20d212b ]

Checking for 0 is insufficient: when an SKB without a batadv header, but
with a VLAN header is received, hdr_size will be 4, making the following
code interpret the Ethernet header as a batadv header.

Fixes: be1db4f6615b ("batman-adv: make the Distributed ARP Table vlan aware")
Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/net/batman-adv/distributed-arp-table.c b/net/batman-adv/distributed-arp-table.c
index b6cfa78..4f0111b 100644
--- a/net/batman-adv/distributed-arp-table.c
+++ b/net/batman-adv/distributed-arp-table.c
@@ -391,7 +391,7 @@ static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
 		   batadv_arp_hw_src(skb, hdr_size), &ip_src,
 		   batadv_arp_hw_dst(skb, hdr_size), &ip_dst);
 
-	if (hdr_size == 0)
+	if (hdr_size < sizeof(struct batadv_unicast_packet))
 		return;
 
 	unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;