net: flow_dissector: fail on evil iph->ihl

[ Upstream commit 6f09234385 ]

We don't validate iph->ihl which may lead a dead loop if we meet a IPIP
skb whose iph->ihl is zero. Fix this by failing immediately when iph->ihl
is evil (less than 5).

This issue were introduced by commit ec5efe7946
(rps: support IPIP encapsulation).

Signed-off-by: Jason Wang <jasowang@redhat.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Petr Matousek <pmatouse@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jason Wang 2013-11-01 15:01:10 +08:00 committed by Greg Kroah-Hartman
parent 2b58df72ac
commit 161f4a458c

View file

@ -35,7 +35,7 @@ again:
struct iphdr _iph;
ip:
iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
if (!iph)
if (!iph || iph->ihl < 5)
return false;
if (ip_is_fragment(iph))