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

Greg KH
2008-02-06T23:59:53Z

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

[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@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
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;

--