[patch 12/73] IPV4 raw: Strengthen check on validity of iph->ihl

[Greg KH]

2.6.23-stable review patch.  If anyone has any objections, please let us know.
------------------
From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

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

[ Upstream commit: f844c74fe07321953e2dd227fe35280075f18f60 ]

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@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 net/ipv4/raw.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -270,6 +270,7 @@ static int raw_send_hdrinc(struct sock *
 	int hh_len;
 	struct iphdr *iph;
 	struct sk_buff *skb;
+	unsigned int iphlen;
 	int err;
 
 	if (length > rt->u.dst.dev->mtu) {
@@ -303,7 +304,8 @@ static int raw_send_hdrinc(struct sock *
 		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;

-- 
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/