From 1c9b7aa1eb40ab708ef3242f74b9a61487623168 Mon Sep 17 00:00:00 2001
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Wed, 9 Jan 2008 03:51:59 -0800
Subject: [PATCH] [ATM]: Check IP header validity in mpc_send_packet
Al went through the ip_fast_csum callers and found this piece of code
that did not validate the IP header. While root crashing the machine
by sending bogus packets through raw or AF_PACKET sockets isn't that
serious, it is still nice to react gracefully.
This patch ensures that the skb has enough data for an IP header and
that the header length field is valid.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/atm/mpc.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/net/atm/mpc.c b/net/atm/mpc.c
index 2086396de1775..9c7f712fc7e9c 100644
--- a/net/atm/mpc.c
+++ b/net/atm/mpc.c
@@ -542,6 +542,13 @@ static int mpc_send_packet(struct sk_buff *skb, struct net_device *dev)
if (eth->h_proto != htons(ETH_P_IP))
goto non_ip; /* Multi-Protocol Over ATM :-) */
+ /* Weed out funny packets (e.g., AF_PACKET or raw). */
+ if (skb->len < ETH_HLEN + sizeof(struct iphdr))
+ goto non_ip;
+ skb_set_network_header(skb, ETH_HLEN);
+ if (skb->len < ETH_HLEN + ip_hdr(skb)->ihl * 4 || ip_hdr(skb)->ihl < 5)
+ goto non_ip;
+
while (i < mpc->number_of_mps_macs) {
if (!compare_ether_addr(eth->h_dest, (mpc->mps_macs + i*ETH_ALEN)))
if ( send_via_shortcut(skb, mpc) == 0 ) /* try shortcut */
--
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