From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Sun, 6 Jan 2008 07:14:44 +0000 (-0800)
Subject: [IPV4] raw: Strengthen check on validity of iph->ihl
X-Git-Tag: v2.6.24-rc8~54^2~31
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f844c74fe07321953e2dd227fe35280075f18f60;p=linux-2.6

[IPV4] raw: Strengthen check on validity of iph->ihl

We currently check that iph->ihl is bounded by the real length and that
the real length is greater than the minimum IP header length.  However,
we did not check the caes where iph->ihl is less than the minimum IP
header length.

This breaks because some ip_fast_csum implementations assume that which
is quite reasonable.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 66b42f547b..e7050f8eab 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -271,6 +271,7 @@ static int raw_send_hdrinc(struct sock *sk, void *from, size_t length,
 	int hh_len;
 	struct iphdr *iph;
 	struct sk_buff *skb;
+	unsigned int iphlen;
 	int err;
 
 	if (length > rt->u.dst.dev->mtu) {
@@ -304,7 +305,8 @@ static int raw_send_hdrinc(struct sock *sk, void *from, size_t length,
 		goto error_fault;
 
 	/* We don't modify invalid header */
-	if (length >= sizeof(*iph) && iph->ihl * 4U <= length) {
+	iphlen = iph->ihl * 4;
+	if (iphlen >= sizeof(*iph) && iphlen <= length) {
 		if (!iph->saddr)
 			iph->saddr = rt->rt_src;
 		iph->check   = 0;